I bought some seed potatoes (Kestral and Sante) on the 12th Feb and they've been chitting on the kitchen windowsill and in the spare room...
...and this is what they look like now:
Kestral are a second early, while Sante are a main-crop potato. I wasn't really sure what I was doing when I chose them, but my local hardware store had their seed potatoes on display and I was tempted! Having read around a bit, it turns out I picked 2 very good types, with good pest and disease resistance.
The other thing I've learnt is that whereas I'm used to buying "new" or "old" potatoes, growers have 3 types:
1st Early = New potatoes, eaten small and early summer
2nd Early = New potatoes, grown larger and harvested towards the end of summer
Main-crop = "old" potatoes, harvested in the Autumn onwards and the only ones that store well.