From Humberside's nearest railway station, you can get to London in under 2 hours, then to central Brussels in another 1hr45mins, at a return 1st class fare of under £200.
Oh really?
Barnetby - Doncaster: 55 mins
Wait: ?
Doncaster - Kings X : 1 hr 46 mins
Or, if you prefer
Barnetby - Newark: 58 mins
Wait: ?
Newark - Kings X: 1 hr 38 mins
Any reasonable waiting period puts both routes over 3 hours, by my arithmetic. And how does one get to Brussels from Kings X? The Eurostar? That'll be a lovely trip across London on the underground then, and another wait at Waterloo.