You MUST obtain written permission from your lender otherwise you will be breaching your mortgage deed. They will only allow you to offer a fixed term AST of 12 months maximum so "guaranteed rent" is out of the equation. Agents such as Northwoods offer guaranteed rent but they should ask if your lender will approve their terms and the answer would be "most unlikely".
Originally Posted by erica-65
You would in effect be handing over your property on a commercial type lease, and you will need to take good legal advice first, but I would be leaving well alone.
The advice I give should not be construed as a definitive answer, and is without prejudice or liability. You are advised to consult a specialist solicitor or other person of equal legal standing.