You can mortgage your property against a land charge however you want. The money from it is not earmarked. That means if you take out a (Fordward) loan, you can sensibly use it to repay an old loan that is due. If you have taken out more credit than you need for this purpose, you can basically do whatever you want with it. The catch is that unused money still costs interest, if applicable. For example, if contractually agreed, you could make an early repayment as soon as possible, invest/renovate the house further, or invest the amount.