Thanks to everyone for the replies, there are answers in there (eg "Skiing on a North facing slope in January is a very different experience to a South slope in April")to questions I didn't even *know* to ask!!
I'm planning on going dry-slope skiing over the summer/ autumn to get practice and exercise, so I wouldn't be buying boots or skis straight off, although I may buy boots later on, but I'll probably still rent skis/ board for the first couple of holidays.
I wouldn't be looking at off-piste initially, so compasses etc probably won't be necessary
Thanks also for the links, hopefully now I can go into shops with a little more confidence that I'm not going to get fobbed off with whatever the salesperson wants to shift...!