niknak
I would question your times a little. Check-in at a small regional airport can be as little as 20 mins prior to dep. (Indeed that's what SN Brussels Airlines post from a larger BHX to BRU). Block time HUY-BRU in an EMB-145 would be about 1:20. As for waiting a half hour for your bags at BRU, I very much doubt it. I often fly into BRU and nine times out of ten my bag reaches the carousel before I do. Finally, there is a frequent and rapid train service from BRU airport to the city centre. No need for buses or taxis.