Selling a property without Planning Permission

A commercial venture, they the intention is a short term flip is going to be more risky for the bank. An owner occupier is less risk, as they will hold it for longer typically.

@JimmyVik got the mortage without issue as the loan reflected the value. Banks couldn't care whether a property has planning or not. Post saying "impossible to mortgage" miles off the mark. Banks just won't be interested in paying full price for a house that comes with inherent risk. Why would they, its paying over the value.

The advice to the OP regarding applying for retention was based off the initial impression that the OP was selling the property. They'd have to own it to apply for that!

Well you can do that in general for planning permission alright but why would you bother?

You'd be a bit thick to go and pay the application fee to regularize someone else's planning deficiency and then they might either turn around and sell it to someone else, or demand more money. If you bought it subject to it becoming regularized then maybe. But other than that you wouldn't do it. And the seller wouldn't want to sell it to you on that basis anyway. Because if you didn't regularise it, you'd get your money back but the buyer could be an unwanted tenant.