My parents just told me that the extension they did hasn't got building regs approval so I'll need to get indemnity insurance when they die and I want to sell – they paid a manager to look after everything who ended up ripping them off.
When I sold my last house was told I needed to get indemnity insurance to cover the fact that my garden might be contaminated as there used to be a battery factory nearby. As no neighbours had heard of there being a potential problem and the factory had been replaced by nice flats I said no thanks so the buyer paid the £600 in the end.
I also didn't have a certificate for my extension on the house as the council sent it to the architect who then didn't send to me and I forgot about it. The council sent me a nice letter saying all OK and that was that.