Hi Gaz,
I use Carribean Red Halberneros, Habanero Burkina Yellow. These are only two of the different chilli plants that I have in my greenhouse. I grew some Tepin plants, which have small purple fruits on them and are very hot also. Birds Eye, Cherry bomb (which are mild, but I found several that blew my head off too). Maybe that was something to do with cross pollination or something like that. I have never tried the chocolate scotch bonnet seeds though.
Mark I usually save seeds from the chillies the year before and then replant them or buy in what I fancy. The halberneros that I have grown this year came from our local farmers market, only 50p each. OR you could always visit The Chilli Festival at West Dean. Sadly you have all missed it again this year, it is usually held on the first Saturday and Sunday in August. Had a great time there!