Basel is the best one, about an hour from Freiburg. But you could fly into loads of places -- Zurich, Munich etc and get to Freiburg easily enough. You could easily drive to Freiburg too. It's about 8 or 9 hours from East Sussex.
I’m resigned to missing out on the away leg as I’m away on holiday and arriving back at LGW on the 6th ie day before. Even if I could get a ticket (far from likely) the thought of immediately getting onto another plane after a long flight, towing a suitcase full of dirty washing, doesn’t appeal.