Rory, if you are just getting started.... a hobby store can be a drain on the pocket book! Not saying that's a bad thing! I find between online shopping sites, ebay and the local hobby stores, my wallet is consistently lighter.
In regards to scale, again this is just my preference, I prefer 1/48 primarily, I am building my first 1/32 Bf-109G-6 and love the amount of detail with it, but I don't have a lot of room for that scale. I tried a few 1/72 and I just don't have a delicate enough touch for the small detail. To me 1/48 seems to be a good middle-ground, as far as detail, cost of kits, and range of selection.