Welcome to the forum and the world of all grain.
It can be both brilliantly rewarding or a complete disaster. Don't be put off if it doesn't work first time.
Munch, you can make a perfectly good mash tun out of a 25 or 30 litre plastic FV, add a tap as low as possible and get a bit of thin ally sheet, cut to fit just above the tap and drill a load of small holes in it. Support using some stainless alen screws and insulate with the stuff you put behind radiators, job done for only a few quid.
Good luck and enjoy the results