I am currently going through a remortgage with the same lender. It all went through OK. I then asked for additional borrowing and they have asked for a property valuation to see if it matches what I have valued my house.
I have done a lot of work to the house and it has all been to building regs. In my basement I have laid floors and put a toilet under the stairs. I have never had it seen by the council or got it signed off or confirmed it doesn't need signing off.
I just wondered what the remit of the surveyor is and if there is anything I should be doing.