Quiet place in or around Brussels to drive on his own

My partner is not at all a confident driver, and he has not driven very much at all since passing his test over 10 years ago. He took some lessons here in Brussels recently, but now would like to find somewhere quiet to practice on his own (or with me) while he builds his confidence. We live in a very busy area and he finds it very stressful having to immediately be alert to everything.

At home (rural area of the UK) people often use old airfields and car parks to practice driving with learners. I was just wondering if anyone knows somewhere like this near Brussels where he could practice to get more confident? Failing that, are there any quiet, small towns near to Brussels that you could recommend for practice? He just wants to practice somewhere less hectic than the city centre. He won't really be driving in the city anyway, so it's not that important that he gets used to crazy Brussels driving.