Try Barnsley market, they have the exotic. Croc, Alli, kangaroo, ostrich, etc, not sure about puffin though but if you ask.
UPDATE: Puffin is a protected bird in the UK, they do cull them in iceland.
Do a quick search on Gordon Ramsey and puffin, he once cooked one.
If it's not broken, let's tweak it a bit and make it better!