Yes you're absolutely right, it was fortuitous! In retrospect I'm very grateful that things worked out that way.

I think either Spain or France could be great, whichever you end up choosing. Overall I'd just say that it's best to choose a place that's either walkable or has good public transport for your first solo trip, just to cut down on the stress of finding your way around. Also choosing somewhere where most people speak English (or you can speak the native language) is helpful. So most big cities in Europe. I've been to a couple of smaller places in Spain where not as many people spoke English, but I was still able to get by. Anyway, sorry for the rambling comment, but I hope it helps!