Hi I would be careful just filling in a contract yourself. Are you the tennant or the owner? You need to check out the law on this before you sign anything.
I agree, you need to be very careful with what you are signing. It is worth spending a few quid for a lawyer to read it through and make sure it is all fair and square.
I would get someone to check it out. If it’s in the Costa del Sol area I could recommend a lawyer they have offices from Nerja to Manilva all along the coast and you could find out how much it would be before committing to anything as they give the first consultation free. They have a web page. manilvasolicitors.com, You could try them first it won’t cost anything to ask.