I know almost nothing about the ancient belgians, which is a shame because I live in the area where they once lived. There is one name you should remember. Which is Ambiorix chief of the Eburones. He did plan attacks against the romans. He supposedly resided in the village we call Tongeren. Not to long ago a book was published 'de oude Belgen' by ugo Janssens. The book is in Dutch. I don't know if there's a translation available. But you never know it can come in handy. Sorry for spelling mistakes but I'm on mobile.

edit: found some more stuff which might come in handy, the problem is that most of them are not going to be in English

La Belgique au temps de Rome : des tribus celtiques au royaume franc, by André Wankenne, 1979

Colchester Before the Romans or who were our Belgae? in Colchester archeological trust, volume 14, 1982 by Christopher Hawkes.

Although, I'll say it again, I'm not an expert on the subject I think that there aren't many sources on the Belgae. Even in belgian history classes we see almost nothing about the people who lived in the Belgae area. History classes tend to focus more on Roman history, perhaps because we don't have many sources about the Belgae and mostly Belgian historians are interested in the subject.There really isn't that much known about them. But that's just my educated guess.