It is about an 80 minute drive from Lourdes to Gavarnie, with hairpin bends, and steep cliffs at the side of the road (so take a travel sickness pill if you are slightest bit prone)! It is worth it though, for the air. Lots of places to walk, snow in the winter and early spring (with both cross country and downhill skiing). It was a crossing place to Spain in the past, for pilgrims to Compostella, and the tiny church reflects this. Stay down wind of the donkeys though, and don't be tempted to take a dip in the icy cold stream.
There is a lovely craft shop beyond the main street as you walk into the hills, well worth a visit.