There seems to be some super cheap one way or return tickets out of Brussels CRL airport to many places in Europe for as low as £12
https://www.google.com/travel/flight...RpgetffivB8g86
https://www.google.com/travel/flight...brb9umawaNjPBA
I haven't checked them all out but it seems to be working for a lot of cities, PRG, VIE, MXP and many more