Out of Perpignan you'll cross through farmland until starting to climb over the Pyrenees. The crossing is at a low pass with some interesting history and you'll find yourself into Spain.
Spain is the second most mountainous country in Europe, so expect very little flat riding until you hit the Atlantic Ocean. There is however a huge network of dirt roads so finding good trails becomes much easier.
There's a steep and high pass to cross to get to Olot, then a few kilometres of disused railway line, around two reservoirs and then through the town of Vic as you pickup parts of one of the Camino pilgrimage routes.