Consider this. If you own a property in Spain, and decide to move back to the UK and buy a home, you will pay an additional 3 per cent of stamp duty land tax (SDLT) if you buy before selling your home in Spain. The good news is you can apply for a refund once you sell your home in Spain, but still. Tax, tax, tax, wherever you go.
As Mark says, the additional SDLT can be refunded once your Spanish property is sold, but you only have 36 months in which to do this, although this may be a bit longer if you buy before 25th November 2016.