Normally contracts will stipulate that Spanish Courts will have jurisdiction over disputes stemming from Spanish property contracts and so the case would be heard here. It may however happen that if the developer sues in the UK and you accept jurisdiction then it will Uk Courts taking charge of the matter although not necessarily UK laws will apply as Spanish law may be enforced on the case. As you see it can get complicated but this complication is beneficial for the consumer, you in this case.

I find the above blog confusing as it seems to suggest Developers can go direct to british courts without going via Spanish first. ( I accept they would go to British later)
My PPC says only Malaga court is allowed as court to settle disputes. This is a pity as British courts are much stricter on breach of contract ( eg 1 day late is breach) whilst Spanish have it seems different attitude to time! Also they are considerably cheaper, although legal advice similar in cost