In reply to mikegbpf:
In N Wales there are often a lot of rocks under the thin layer of soil so as you are car camping where weight is less of a issue invest in steel pegs and take a hammer. The lightweight aluminium pegs usually supplied with new tents will just bend and are difficult to get in. This also applies if you are camping on frozen ground.
Get good quality insulation mat either a Thermarest or Karrimat and a 3/4 season sleeping bag rated to at least minus 10 degrees for that time of year. I'd rather be too hot than too cold. Beware of cheap sleeping bags which can be cold - you get what you pay for. Personally I prefer down fill to synthetic. A silk liner is a really worth while investment - keeps you warmer and stops the sleeping bag from getting smelly.
A pee bottle is very useful and saves you having to go out in the night or if it's raining.
For washing up tufts of grass work really well. The earth round the root acts as an abrasive and the grass is an excellent cleaner. (obviously if you have non stick pans be careful not to scratch them), for this reason I prefer steel. It's a bit heavier but not significantly. Don't take too many pots and pans. You won't use them. As someone has said practice cooking on your stove in the garden at home.
Take food that is quick and easy to heat up. You don't have to buy expensive off the shelf cook in the bag ready meals you can make the ingredients up yourself for a fraction of the price before you go. Make certain you keep your matches dry and take a cheap cigarette lighter as a back up. If cooking on gas take a spare cylinder, and if camping in cold weather remember that propane/butane doesn't burn as well as liquid fuels like paraffin or petrol, but for the latter is potentially more messy and take a cleaning rag and prickers to prevent carbon build up in the jets.
So far as clothing is concerned go for breathable waterproofs, and reasonable quality walking boots. (preferably Gortex or similar lined). Take spare socks - I've found the inexpensive JCB work socks are great for walking and hard wearing - you can get them on line or at Morrisons. Don't wear jeans, get quick drying walking trousers. Wear a base layer (ideally one that wicks), a mid layer of fleece or similar, and a fleece jacket.
Don't take too many clothes, you really only need changes of pants, spare socks, one spare base layer and one spare mid layer, so that they will keep you warm next to you skin at the end of the day, if the others get soaked
Good luck and enjoy