Most mortgages in the UK are portable. This means that you can transfer your mortgage from your current property to your new home you’re purchasing. Before your lenders will approve the transfer of your mortgage, they will want to value the new property first. But you may need to borrow more to buy this new property, plus there may be fees to pay for the transfer. However, down-sizing may be a problem, depending on the loan to value calculation for the new property.