It's impossible to answer this question without knowing the interest rate and the mortgage term. (You've also not indicated how much you actually need to borrow. You won't get a 100% mortgage, so you need to deduct your deposit from the sale price before calculating the mortgage repayments).
Please remember that if this mortgage is secured on the B&B then you will be paying commercial interest rates, commercial fees and will probably get around 75% of the value of the property at best.