The Four Burrows wind farm in Cornwall has 15 turbines each generating 300Kw total 4.5MW
SizeWell B has a capacity of 1188MW
So you'd need 264 Four Burrows' to make one Sizewell B
BUT you cannot whistle up a storm when it's half time at the cup final so you'd never be able to run the entire country
We currently have 72GW generaing capacity so that'd be 16,000 wind farms like Four Burrows if they could be relied on to produce energy when required.
Wave power also suffers the same controllability issues but the energey generation capacities could be useful theres a project here:
http://www.marineturbines.com/projects.htm
which could generate up to 300MW but remember that's peak it can't do that when you need it.
If you've not already tried it have a go at solving the UKs energy requirements on the BBC's energy Calculator program here:
http://news.bbc.co.uk/1/shared/spl/hi/uk/06/el ectricity_calc/html/1.stm