BritGirl,
Some very good advice here, and I'll echo a bit of it: take an NRA personal protection course. I just went to one here last weekend (both because I need the certificate to get a Mass. CCW and because my fiance and her daughter were attending it) and they covered pistol safety, fundamentals of pistol shooting, and the legal (for NH/Mass) ramifications of deadly force in self defense. I would also recommend getting a Louisiana CCW even if you don't think you'll ever use it - if nothing else it will simplify things if you are ever pulled over for a traffic violation going to/from the range for practice.
One other thing to consider is getting involved in competition. In my (admittedly limited) experience, those getting a gun purely for home defense tend to practice for the first few months but tend to drop off when their skills (and enthusiasm) plateau. IPSC, IDPA, or even Bullseye competition on a regular basis will keep you motivated to go to the range regularly, and (of possibly even more benefit) will introduce you to others from whom you can learn even more. Besides, they're also just plain fun.