Is there anything to do in Munich?!
haha! Of course there is! I'm sure you've checked out all the beer halls by now.
Go to the Hauptbahnhof and check out the Eur-Aide office, ask them for advice on things to do in the bavarian area-- grab a bayern ticket, I think for 4 people it's like 10 euros or maybe less each, good for all day train travel anywhere in Bavaria. You could go to one of the Ludwig Castles; my favorite is Schloss Linderhof, but Neuschwanstein is, of course, very popular. If you're really into grandeur you could try Herrenchiemsee, which is an attempted one-up of Versailles. Or you could take a day trip to Salzburg on your bayern ticket as well.
There is SO much to do in Bavaria!!
Have a great time!
OH-- if you're still looking for a flight to England, RyanAir has a flight from Salzburg to Stansted. I don't know if you have tried that but it may be worth a look (to my recollection it's far cheaper than flying out of Munich.)