Chris Wren +1 - you will get an outstanding tour with him; IIRC he's been involved in the project since the 80s, soon after the bunker was restored and re-opened around the mid-late 70s (when I was on my first tour in the RAF at Uxbridge).
And the number of "The Few" remaining is, of course, dwindling - those remaining are all over 90 years old and, of the names of the 2,936 aircrew from 15 countries inscribed on the Battle of Britain Monument at Embankment in London, the total left, I think, now numbers fewer than 60.
MG Mark