I have done, including for ten days this summer. Got back three weeks ago from Almería province in Andalucía. The way round it is to turn off wifi and use 4G, which is really good in Spain. Borrowing a chunk of wifi at hotspots and hotels is bloody useless. As from next summer you'll be able to use your UK data allowance. Up to now I've taken Vodafone Eurotraveller, which allows you to use your UK plan for three quid a day. Sounds a lot, but I use the internet all the time and have to ring my mum back in the UK a lot. Even if you're in a 3G area only, it's better than wifi hotspots. It's great to just pretend you're at home for the cost of just three quid a day! I think I might have just left wifi switched off all the time I was there except when I was at my mate's house logged into his broadband.