£250 for half of everything you grow sounds like your mate is getting a right result. so your going to need to buy materials to section of part of the garage, a couple of fans lights, soil ferts for veg and ferts for flower, mylar or paint and beans, i think you need to do alot of research befor you start this project, with £250 you could have a great little setup, but don't rush into it you need to do your homework properly, best of luck.