I'm sure Biggin is a lovely place to fly. I may have had the details wrong but training at an airport of that sort you will, on a regular basis, be asked to sit doing nothing on the ground (paying flying rates) whilst the tower prioritizes an aircraft that those who run the business consider more important.
I fly from Biggin (didn't qualify that long ago, ~60 hrs TT), usually on Sundays, and could count on one hand how many times that's happened. Maybe it's more common during the week, but I've seldom found it to be a problem.