What are the regs on selling block time in the UK? If they're manageable, buy out his half and find a block time partner, that way you get to call the shots and have priority. Sell the block time in 1000 pound chunks; that way you're never more than 1000 pounds away from terminating the agreement.
Theoretically in Canada your aircraft has to be registered commercial to do so. So instead, we "loan" or aircraft, on a "pay your own expenses" basis and your close friend gives you an annual "gift" for being so kind. You do have to have the person named on the insurance policy.