Bank Holiday Camping

Some friends and I have decided to go camping over the Bank Holiday, probably down to Somerset. This is going to be the first time I have camped in over 10 years and even then it was minimal. We are borrowing a tent to see if we actually like it before blowing a fortune on something that we will only use once. Still need to buy inflatable matress (I'm 31 and I don't think my back will take sleep on a mat) and a couple of sleeping bags. Have no idea what else we'll need so going visit Go Outdoors in Oxford for inspiration.