The first thing noticeable about UK is its weather and the persistent rain. Once you have sorted that out as a foreign traveler or a local person camping within UK, (for a UK resident that should not be a problem at all), you are set to have a great time while backpacking.
The bare essentials for a good trip include but are not limited to
Spare Underwear: Ignored and often paid the least attention, having comfortable underwear is extremely important. For sake of clarity, we are also including socks in the underwear list. Your underwear is your first layer of protection and remains in touch with your skin. Chances of body odor are the highest hence you require to pack some extra sets. The fact that good underwear is of utmost importance while walking or camping makes it necessary that you are comfortable with your undies. For socks, although expensive but having 4 – 5 pairs of quality wool socks will be able to last you for a long time. They are resistant to body odor and are easy to dry making them ideal companions.
Shoes: An extra pair of shoes is highly recommended though not always necessary. Get walking shoes that offer grip and are water proof. Rubber boots in case of heavy rains may help as well. A good trick is to pack a small waterproofing gel or liquid which you can apply to offer ability of water proofing if your shoes do not have it.
Clothing: The lesser the better and avoid heavy clothes. Dress yourself in layers; that decreases the weight that you have to carry and offers flexibility for various weathers. Avoid heavy clothes and jackets and turn to lighter alternatives. Have one water proof jacket that you may require if it rains.
Accessories: Sun glasses, sun screen, hat, a pair of gloves, key chain flash lights, multi-purpose tool kit like a Swiss knife, water bottle, a hiking specific watch (if possible), an umbrella, a lighter, spare batteries, toilet rolls, first aid kit, hand wash, tooth paste and tooth brushes (mouth wash, floss if and when required) and cell phones (as well as other accessories related to cell phones including tablet phones, tablets, lap tops and other communication items that are carried around by people in daily life) are important accessories that you can carry around within your clothes or on your body.
Personal Medication: A very important item to have in your back pack is any sort of medication that you are on along with proper notes for other people in case you need help. It is also advisable to carry extra medication; this tip can come very handy if you end up losing or dropping your medicine. You can carry some other prescribed drugs as well for known conditions or over the counter medicines for headaches, fever or other routine problems that you may face in case you are camping). For couples travelling on camping family planning pills and other such personal items are also noteworthy of your time.
Tent Accessories: Now we come to things that will be required by you for your tent for both normal use and in case some odd event happens. Spare tent pegs, mallet or hammer, source of light (a lantern, electric chargeable battery based torch), duct tape (a surprising item in the list but the fixing powers of duct tape are beyond almost any known item – you will be surprised by how useful it can be in situations where almost everything else fails), cleaning brush, and some electric equipment will be required in case you want to charge your mobile phones or tablets. There are companies that make solar panels (small solar panels which can be easily carried along with batteries) which are handy electrical supply for you on the go.
Sleeping related items: The fact that you will be sleeping in your tent for a couple of days at least means you need to pack some important sleeping items in your bag pack as well. Sleeping bag, sheets, pillow, ear plugs and sleeping masks are required to say the least. In case you prefer to sleep on a camp bed pack the accessories related for that as well. Although not directly included in the list but you can include air fresheners and odor repellent items (not much, only little) if you feel that you will have trouble sleeping if there are body odor in the tent.
Kitchen Items: Although it is better to carry as little equipment as possible but if you are wishing to have a wholesome camping experience, kitchen utensils and items are necessary. Stove or BBQ are a must and will be required, gas stoves are also an option in case you are not interested in cooking on natural fire. Bin bags, spare lines to hang food, insect and bug repellents, some cutlery, pots, charcoal, wipes and tin openers will be almost mandatory. Regular back packers and outdoor campers often have travel kitchen items placed separately. You are advised to stay away from proper china, in order to both be environment friendly eco-friendly re-usable dishes, glasses, spoons, forks and plates are the way to go. If you are having trouble finding them, try to find the lightest and strongest kitchen wear. In case you have washable dishes, you probably would need to carry a big bucket or other item related to such where you can wash your dishes. Use a multi-purpose bucket, not only it will help for washing kitchen items, if properly cleaned it can also be used for laundry.
Children items: If you are travelling with kids, the whole paradigm completely shifts. The fact that children require personal and special care means that you are bound to carry some extra stuff in your back pack every single time you plan to spend some time in the open. The requirements change with the age of children with infants and young children requiring totally different things from their grown up siblings. In case of such a situation, you should try to overstock rather than understock of their basic and routine supplies. It will also be helpful to have back up supplies of necessary items available close-by (probably keeping them in a car). It is better to get some snacks and brands that children like and are used to, not only it helps as a motivating factor, it keeps them in touch with their favorite things. Such an approach keeps their interest in camping otherwise they may start hating camping and see of it as a chore and a burden rather than an enjoyable experience. Remember, if you are not traveling with wi-fi and internet, they already are sacrificing a lot!!!
The check list is just a general guideline and is different for different people. Experienced campers often are able to make the best of limited resources choosing to travel light and making the most out of their limited resources. The purpose of camping also dictates the stuff that is going to be part of your back pack, if you are on a leisurely family trip, you may require carrying extra stuff. On the other hand if you are out for a more rugged and natural experience, you have the option to travel light and leave some of the luxuries of life.
Your safety though should be your primary concern in all cases – have fun but be responsible.