Hey I live in Spain and I travelled to Barcelona a couple of years ago. It's a big city which is a little overwhelmed with tourists (especially around Las Ramblas and the port area). Those areas might be a little tricky with a frame, although the Spanish are, in theory at least, used to seeing people in wheelchairs, with frames, etc (although in Sevilla at least, they're not very used to seeing younger people using these aids). I'm not sure how hot it'd be in September. It says you're from Inverness, so I guess it'd be considerably hotter than there, but nothing compared to what I live in Sevilla. I think the best advice for hot weather is just to plan your day around staying indoors during the hottest hours, which are generally from lunch to evening. Early mornings are great, as are balmy, breezy evenings. And siestas exist for a reason y'know...

Going to Greece next week. Bought the TRILINK portable neck fan from amazon. Trying things out to keep me cool on bus transfers etc