Hey Atomic- there are LOADS of varieties, and it really depends what you want in a potato! (If that doesn't sound too weird!).
A lot of people ask me why I bother growing potatoes when they are so cheap to buy. Two answers, really. Firstly, the taste of home-grown is sooo much better than from the supermarket - I mean you're talking way more interest and differences in flavour than you can buy there, to the point that if you are not careful you will just start munching them straight out of the pan! Secondly, potatoes are great for turning up the soil in a new patch so they do a load of digging for you!
Here's the bad news: you're a bit late. You put very early potato varieties in during March, intermediate varieties (called second earlies) in during early/mid April, and main crops during May. However, since it's been a cold start to the year, you will probably get away with some main crop varieties if you get them in asap.
My salad/maincrop potatoes this year are: Pink Fir and Ratte. However, if you live somewhere warm and wet, I hear great things about Sarpo potatoes, which are supposedly very blight-resistant. (And far from being something out of the past, blight is a huge problem!)