get the basics for cheap that will see you good to go. If you want to start out on day trips, that would be better as you can learn how to make your shelters but save on having to spend money on a sleeping bag, bivi bag, hammock, thermarest, etc.
So, for a day trip with a brew and some food, you may need a poncho to keep you dry and to use as a shelter. You could pick one up for a tenner. The german ones are pretty good. A cheap bag to store your kit in. 10 quid for an LK35 is a good starter. Next, maybe a Swedish Army Trangia, shopp around you shouldn't spend more than ten quid. Use a small pop bottle to stow your meths in. A mora knife, less then a tenner. Get down the local hardware and DIY store and look for a folding saw, I have a Spear and Jackson that locks in both the open and closed positions and cost three quid.
You can use a plastic beaker for your brew, won't break and they are cheap to buy. Shop around. Pick up a few bic lighters, three for a pound types. Grab a spoon from the kitchen drawer. You've now got a good outdoor kit for not much, and you can expand on it. Make sure you have a first aid kit of some sort if you are using knives.