Good advice Yorkie, thank you!
I was actually working out what to do when you posted this, looking at various comparison sites, poking around the 'maze' etc., and yet another check (the seven hundredth) with EDF seems to have got me the best deal - fixed for two years at any rate!
The new Ofgem 'cap' is confusing to say the least, and not easy to understand for sad nerds like me and my spreadsheet even, so goodness knows how many pleasant citizens are being ripped off without knowing how or why!
Anyway, thanks again! A glass of red here to celebrate!