I certainly agree with Lawbird Lawyer, a Spanish will is the way forward, and would like to add that the best option to allow your friend to live in your property until he passes away, is that, in this will, you designate him as your inheritor only for the usufruct (right of use for life or life interest) and your family in the UK as the bare owners. This would allow him to live in Spain and your parents would know that upon his death the ownership would revert straight into your family.