Hi Sleepy, welcome to the forum
I'm not entirely sure if the laws in Scotland are different, but certainly in the rest of the UK if you sell a property with security against it, the solicitor who deals with the sale is duty bound to clear those debts before they pay you anything thats left over, if there is anything. In the case of negative equity, you may be forced to repay those loans at the point of sale. Maybe a call to the loan company to ask them if they would change it to an unsecured loan would be in order.
The WHV is a great route to take, as you can take other work if the money runs short, while looking for 'the' job to secure a more permanent visa.