Wheely if you haven't had a look yet Decathlon do some good deals on camping things. We also use lots of things we already have in the house.... my best pans & kitchen knives get packed, just because it is easier to cook something and therefore we are less tempted to eat out.
Take a blanket / rug for under your sleeping mats - it keeps you so much warmer. Also a beanie hat and hot water botles for night time if the weather is looking a bit mixed. Other top tip is if you get a dry day open the tent up to air and throw the sleeping bags (unzipped) over the guy ropes. Keeps everything free from conedensation.
Try to get a sunny in the afternoon pitch.... means you get a lie in as the tent doesn't get too hot in the morning and you are warmer in the evening. Also stay away from standing water and treelines if you are prone to midge bites ( they hate wind)
Don't forget your bottle opener!