Is the creche for full time care or just part time or occasional care (you don't mention you working too)? If it's full time, then it's highly likely you won't manage to find a "Belgian priced" creche (that's 450-600 euro per month) and you'll be left with "expat priced creche", of which 2 chains operate in Brussels, both in the eastern and central areas of Brussels, not in Uccle, though maybe there is something in Uccle I don't know about. If it is part-time or occasional, there are still cheap alternatives as little as 20 euro per day, several options on the east side of Brussels again. There are several expat priced creches near to local schools which high number of international children in them, it's not really going to be that problematic dropping off at creche and then school, nearly all Belgian resident families do the same who have children age 0-3 and 3+.
There are a few creches next to schools, often run by the same charitie which govern the schools, they are "Belgian priced" ones and you would have ideally had to reserve a place at 6 weeks pregnant.
Many local schools have high percentages of international children in them, some up to 40%, depends on the school whether you'll make friends with the parents. In Anderlecht, unless you fit into a specific ethnic group, it is highly unlikely you'd be mixing socially with many of the parents there, whereas if you choose the right area, you might indeed get a good group of friends from contacts at local schools. Many if not the majority of children at the lycee francais arrive by school bus, so I'm not sure how sociable the parent circles are there. At BSB the parents are incredibly sociable, lots and lots of activities for them, for the children after school including activities which non pupils at the school can attend in English, especially handy if your child is at a local French or Flemish school and they only get to speak English at home.
Without knowing the exact address in Anderlecht, I couldn't comment on how viable working there and having children at school in Tervuren, or Uccle or WSP is. My husband works on the Anderlecht border and takes 30 minutes to get to work, we live in WSP. We used to have a child at BSB.
There is only one private French school I know of at primaire level in Belgium, it is about 50km from the centre of Brussels, called Schola Nova - curriculum heavily weighted with Greek and Latin, yes even for 7 year olds.
Ixelles could be quite problematic to live and work in Anderlecht, again it depends on where in Anderlecht and where in Ixelles as they are both big communes. Ixelles is one of the most expensive places to live, more expensive than WSP even, parking is a problem, local schools well you can just about forget it, next year maybe.
if your husband doesn't want more than a 20 minute commute, well then you'll have to accept living in an area without any expat population (well you'll have to look incredibly hard for one) and also many places within 20 minutes of Anderlecht are not areas where I'd live by choice. Berchem-Ste-Agathe is quite nice, if it's the north of Anderlecht, or Sint-Pieters-Leeuw (Dutch speaking). But you're a long way from any bilingual schooling options, the local schools will possibly have not a single English speaking child in them.
I have a child in local secondary, I'm hoping in the next 2 years for him to take IGCSEs in French, Dutch, English and Maths, as an external candidate of BSB. We don't get international school fees paid for (any more) so this is the nearest we'll get to a British education for our other children. If our children went back into the British system now, I'd expect them to be ahead of their peers, especially the 13 year old. Their biggest adjustment would be English spelling with the youngest ones, definitely where they lack the most.
