When you go for your first lesson just wear jeans and a shirt with jumpers as necessary, take your headset if you wish but leave the rest at home the flying school may not think much of you if you turn up apearing to know it all. As for the uniform you wont ever need it unless you take professional training at somwhere like Oxford, your instructors however may have to wear a uniform that depends on the school. I dont think you are entitled to wear eppelets until you are a qualified pilot anyway.