Hi mycatlady! I'll have a go, but others may well do a better job.
If you sell the property, then the money that the purchasers pay to you will probably be paid into the account of your solicitors, assuming you use one.
So if they agree to pay £300,000, they (or their solicitors) will pay £300,000 into your solicitors' account.
From this:
First of all, the solicitors may take off the fees you owe them for their work. Say, for example, this might be £2,000.
Secondly, the solicitors would pay off the balance of the mortgage by paying that amount to the mortgage company. In your case, you say the balance is £68,000, so this is what your solicitors would have to pay to the mortgage company.
Unless there are any other mortgages or charges in place (for example a second mortgage, or if someone else has a form of 'charge' over the house) then the balance would be paid to you.
So on these figures,
- your buyers would pay £300,000 to your solicitor
- your solicitor would pay (say) £2,000 of this to themselves and £68,000 to your mortgage company
- This would leave £230,000, which your solicitors would pay to you.
Although you originally borrowed £144,000, the amount left that you owe (the balance) will likely be less because of the payments you have been making to the mortgage company in the meantime. But although you have paid £77,000, the balance won't be £77,000 less because only some of that will have been paying off the actual amount (the 'debt' or the 'principal amount'); the rest will be paying interest to the mortgage company.
Does that help?