It's a great area for cycling, although I've never ridden a Brompton. Immediately round Avignon the terrain is rolling, no great hills. If you venture further afield, the Luberon is great (with a well signposted cycle route, but it gets quite hilly). Round Uzes is lovely. Basically Avignon is in a river valley, the further you go out, the hillier it gets. Depending on how long you've got and how far you want to cycle, you could do worse than follow the river to Arles, then up to Nimes and take in Pont du Gard. Loads of history, good food, wine, lucky you.