Start Up visa requires endorsement. A B&B won't qualify for endorsement.
https://www.gov.uk/start-up-visa
A B&B also wont' qualify for the Innovator visa and you would also need endorsement.
https://www.gov.uk/innovator-visa
Tier 1 Investor visa requires £2mil to qualify.
https://www.gov.uk/tier-1-investor
The old Tier 1 Entrepreneur would have possibly worked, but that route is closed now to new applicants and there were restrictions on property type investments.
There are hundreds of B&Bs in the UK, many facing closure due to Covid as tourism has not improved since pre covid.