I'd have it done professionally because it will have to go through the controle technique if you stay in France (or the MoT if you don't.)
On top of which if you are carrying kids on it you would want it done properly.
Yes just seen a Combi actually but wondering if this would be better than a 4x4 honda cr-v. We would be doing work on renovating a house if we stayed here. Dont know it a vw combi is better or a 4x4 with a trailer.