Maybe accept the reality that the rental market is broken in the UK. The rent is either to high or too low.
If the rent is high, you should forego any checks (Airbnb). If the rent is low, your checks are too strict (AST).
You should price it in the middle between Airbnb and AST and adjust your checks to “fix” the market. Or sell the property if it’s too much risk for you. There should be much more owners. Mortgage is a scam, the building cost are much less than the price. Regulations and insurances are adding no value. Court system is overloaded as there are too much violations.
The only force driving the price/rent up is demand in a given location. The only force driving the price/rent down are mortgage/affordability/reference checks. The interest rate and slow wage growth eliminated those eligible and you only have cash buyers and Airbnb/Hotel guests on the market.