During the months of July/August the French W coasts are unbelievably crowded. You can usually find municipal mooring buoys for small boats and provision for boaters is far greater and cheaper than in the UK. The N coast of Spain is short on marinas and provision for leisure sailors but there are lots of fishing ports dotted along the coast. Both coasts are open to Atlantic swell, with which UK sailors are not familiar and which frequently prove a challenge.
As soon as you get round the Cap Finisterre corner you find marinas becoming far more frequent, until by the time you get through the straits they are about 25M apart with new ones being added every year.
Are you trailboating, mebbe? Because of the enourmous number of boat movements, there are actually more berths in the popular places in the summer. The crowded places are usually the good ones. Mallorca you can anchor off for ages, S france there's the bay of villefranche, and almost everywhere, once you're in, you can stay for ages. Try anywhere at 2pm, except Nice where blimmin Moorings have nicked almost all the visitors pontoon. Oh, and spain is hot, and the bars have beer and chips, but they do have swiming pools, whereas france is more refained, but not such lux facilities, no swimming pools, and much shorter measures of spirits, ahem.