Good tip. I would like to go even though I won't be able to get a ticket but I'm coming from South. Schiphol is super easy for me from Southampton. The train basically goes from right near my house and into Southampton airport. I could be in Dortmund fairly quickly without too much hassle taking that route.
For us up here it's cheapest. Flights to Dusseldorf aren't cheap from Newcastle. DB train from Schiphol is just over 3 hours. Only €32 return.
Went to see them play at home a few years back on a footy weekend away with the lads. Dortmund itself is a ****ing **** hole but by god that stadium was rocking, best atmosphere I’ve been in the middle of at a game ever! Should have stayed in the Dorf and explored the old town like Bomber and Oz