This might be quicker with some leg work from you.
Most authorities keep all planning documents freely accessible on line. If the question is whether it's been built to the planning you can usually download the plans and compare to what's been built. If it's whether it's signed off you can check that too.
I've tried looking at the plans but it's all quite complicated. Multiple applications with some approved and some denied. The seller is also saying that they only renovated the flat but evidence so far seems to suggest they converted it (and there's no planning that I can find for that)
This might be quicker with some leg work from you.
Most authorities keep all planning documents freely accessible on line. If the question is whether it's been built to the planning you can usually download the plans and compare to what's been built. If it's whether it's signed off you can check that too.
What do you need to know and what council is it?