General kit list
A change of clothes (duh -your first set might get hideously wet!)
Waterproof Coat & Trousers. (I take them in winter and summer, after all our weather is amazing!)
Reasonably decent trainers / boots.
Backpack (plastic bags are not advised, you will have to carry it a short way).
Water bottle (tesco value spring water comes with a free bottle for <20p).
Torch -headtorches are even cooler but if you have a normal torch don't worry about getting another head mounted version to start with
Cash (to pay camping, possible pub things)
And of course your climbing things Harness/Shoes/Belay/Chalk
Additional Winter trip kit list
This is anything in the months of October to whenever it's not freezing cold any more!
Warm clothes - Including hat and gloves especially in winter months. You won't regret taking too many clothes in the winter as it can really be a bit on the chilly side standing around waiting to climb!
Sleeping bag -A quad 4 is probably ideal for the winter and are quite cheap, if you feel the cold don't let the shop assistant convince you it won't get to minus numbers in a barn or in a tent, it will).
Summer trip kit list
Layers are better for summer trips as there is often a much greater temperature variation.
It can also get cold at ngiht if the sky is clear so don't assume because it's 30 degrees at ngiht it'll be 10 degrees at night, it could drop a lot!
If you're going to France you might be OK with a 1 or 2 season sleeping bag, if you feel the cold you might prefer to take a better one, or both. Angry Brian is well known for his sleeping bag which is resembles an over sized crisp packet, without the foil.