Aveline
Just found out that a neighbour has put his flat up for AirBnB and Booking.com. Just what we all dreaded. It's a residential block in a quiet area and most of us are older. He's advertised our parking area and access to our lovely shared garden. We are so upset. The thought of inconsiderate short term letters who won't care how much noise they make or mess they make of our shared common areas is awful. Nothing we can do. He's sneaked it past planning regulations and short term let licence. We'd certainly have registered objections. Och. 
If "och" means you're in Scotland, here he is required by law to be a registered |LL with the local council. You can search the local LL register ( free) to check that. Non compliance = huge fine.
Next, insurance. Residential block properties often have a common insurance policy; if so check the terms of your own for the insurers T and C re commercial letting. If he is doing commercial lets on a domestic-residence policy, he has almost certainly invalidated any claims made on a domestic home policy; and this could put the entire block at financial risk. If you share the same insurance company bring this issue to their attention.
Our development has pages of binding regulations ; ours expressly bans short term lets (like B and B and air Band B)
it also makes building insurance compulsory. We have an elected committee to manage anything from small niggles to expensive buisances, and the Factors. Check your deeds.
If you have a factor, they should have the power to require evidence of an insurance policy.
Next, consider the security of shared entrance/stairwells etc. Our communal main door is locked at all times ( its a condition of insurance policy cover). Will he offer guests an external keylock opened by a code? Will more footfall incur extra cleaning of communal areas?
Landlords charging money enter a whole world of compulsory costs, liabilities, health and safety regulations. Your local council can provide lots of detailed information about that.