Thought just struck me. Have a look at this:

http://www.earlyblues.com/uk%20blues%20festivals%202008.htm

It's a list of UK blues festivals this year. If any coincide with his tour he should contact the relevant person and submit something.

Who is your friend? Got a link to their music? Myspace page or anything? I have been known to organize the occasional gig in London myself....