loco was well expensive. in the end I booked the trip with each of the companies separately. So Eurostar to Paris then SNCF on TVG down to Provence. Eurostar wanted £30 each way to book a place for bike box. Easy to do. Their offices close at 11pm so as last train in, might have to pick bike up next day. SNCF, spoke to them on phone, no need to book a place! Not sure where it will go, but they said it was no problem.
Thanks for the Nimes info, it ended up being too expensive with them when we added bags.