Ah, the famed EU regulations.

It's not just you who wants it out of the way and finished - BA share your view. If only you'd listen to BA's letters telling you that the cancelletion was due to expectional circumstance and to bugger off it would all be over!

More seriously the evidence seems to be that BA (and indeed airlines generally) are being fairly 'robust' in their interpretation of the regulations and a claim in Small Claims Court is likely to focus their attention because the lasst thing they want is for courts to start clarifying things.

Post the details here and you'll get better advice as to where to go.