James,
The ideal of course would be a party that could transport you there and back and include you on their campsite in one go, and someone may well be able to come up with that offer.
However, whilst I can't offer any space in a car to get out there and back, our crew are on Bleu Nord this year, arriving from the Tuesday evening, and then striking camp and returning home on the Sunday evening. As well as the normal crew of responsible adults numbering around a dozen this year, three of my sons are also going (aged 22, 18 and 17) in a Vectra. There will be space in their car once it is unloaded to get you and your brother out and around with them to Arnage, Mulsanne, the town, shops etc, during the time there, so you wouldn't be totally stuck on the campsite or reliant on walking.
You're welcome to join us on Bleu Nord if you wish, assuming that between you and others on the thread the travel bit gets sorted. You don't need to decide here and now, as the arrangement can be taken up at a moment's notice right up to when we're all out there if needs be! That way you can see what others may be able to offer on the thread. Needless to say, quite happy to talk things through with you, your mum and your brother beforehand.
All the best for now,
MG Mark