I don't see why not? Although, they might be reluctant to give a mortgage on land which would be very difficult to repossess and sell.
But the lender would have to look at your total repayment capacity on both mortgages.
Do you have any equity in your home? If so, it would seem better to remortgage your home to buy the land. The rate would probably be lower and the charges might be lower. You might have to pay exrtra mortgage protection insurance which you would not have to pay if you were just buying the land on its own. If it's part of your home, you might pay lower stamp duty. I have an idea that the stamp duty is 9% on all non residential property irrespective of value of the transaction, but others would be better placed to advise you definitively on this.
Check out the tax situation. If the land becomes part of your home and principal private residence, any gain might be exempt from CGT.