Have you spoken to an insurance broker to see what they advise? I don’t understand why having guests in short stays when you are a live in host, should impact on building insurance.
It will impact on home insurance of course. (Have you got home insurance for short term lettings by the way?)
And @Zandra is right if there is a clause in your lease that says you shouldn’t run a business, even if your landlord has given your their tacit permission, that could leave you vulnerable to eviction at any time.
If you want to try and continue, take control. See a broker, if the landlord needs another type of building insurance pay the extra, of course make sure you have home insurance make sure it is for short term lets and offer to pay legal fees to amend your lease to take out/amend the clause about running a business.