That's a sensible idea radicalnan as £70ish is what we are usually charged as an additional cleaning fee if we wish to leave the property without cleaning it. Taking photos is a good idea, but it's difficult to photo grease on pots and pans or smelly carpets!
The thing about arriving at a dirty house is that it's someone else's muck and germs you have to clean. I would take lots of bleach!
What has survived in your garden with minimal or no watering?
What sort of family would you not want to marry into?

