I lived in Belgium for several years and really liked it. Not Brussels though, so I can't advise on anything helpful to you personally, OP, other than saying that in your position I would definitely go for it.
Things I liked, for example:
Friendly people, easy to make friends (I did speak the language)
Socially caring country eg care for elderly, disabled etc people is better funded and nicer than in the UK. I like countries that treat the more vulnerable people well.
Better health care in comparison to NHS - much shorter waiting times, more access to consultants etc. If you have private insurance in the UK then you could find it to be a lower level of luxury though.
Wonderful chocolate, chips and beer in particular, but great food in general
So quick and easy to get to other countries, of course especially NL, Fr and Ger
What I didn't like, for example:
School system where the result is an average of subjects, each out of 20. I don't want to be specific about my DC, but it can lead to a lower average because of one subject, even when not relevant to choice of subject at uni. I'm of course talking about Belgian schools with locals.
Belgian coast is only a few miles long, and most of it is ugly.
The rather silly attitudes of the Flemish towards Walloons and vice versa. But a lot of countries have that sort of issue.
Overall I would happily live in Belgium again. Good luck with your decision!