@Stephen1817 Business rates are required in England if the place is available to rent for 140 days and actually rented for 70 (figures are from memory but close). Authorities are clamping down on this as with business rates you will probably pay nothing and without you will probably pay double council tax. The rues for Wales are even more draconian and I have no idea about Scotland or Norther Ireland.
What do you need?
Permission from financier if you have one
Check with Local Authority as you may need planning permission (this is all a bit weird)
Fire assessment which is likely to require many additional smoke alarms and maybe other changes
Insurance that allows Airbnbing the place
Gas safety certificates if you have gas
Electric safety certificates
Anything else I have forgotten