everything you should need to know about the All Ireland fleadh in August should be here at this comhaltas site. If you look in the section for the fleadh.

Comhaltas web site

It's usally during our last bank holiday in August... the weekend before the bank holiday monday.

Fleadh (All Ireland) info

I'm going to that one too.

As far as which is the closest branch for you... I suppose Cambridge would be the closest - then there's Birmingham, Coventry.

Cambridge branch website

I know it's not near... but here's our branch....
Newport South Wales Branch

Good luck

Ella