@Wendy1757 I'm not in SE25 but have you considered
1) The effect on your house insurance - most will not allow Airbnbs
2) The need for a fire risk assessment and, if following government guidelines, the need for linked smoke/heat detectors in most rooms and hallways?
3) The effect on capital gains tax when you come to sell?
I assume you have no mortgage but if you do you'll need their permission as well.