As above – very much depends what you told the mortgage co when you applied for the mortgage.
Apologies if you know this bit but in case not they work out how much you can borrow by looking at your salary minus credit commitments multiplied by an number (usually 3 times for single applicant and 3.5 time for a joint applicant or somewhere around there).
So, you earn £1500 p/m but have £500 in debt payments – they work on the £1k left.
So, if you have asked to borrow x amount and you have told them that y amount will be used to service existing debt to say lower your debt repayments to £200 p/m they will have assessed the mortgage amount on £1300 salary.
If you do not repay the debts as agreed you are in effect borrowing x amount but with only £1k p/m to service the mortgage which isn’t what they decided their offer on.
If you have told them that you will repay an amount of your debts first using money not related to the mortgage then yes, they will check you have paid off the agreed amount. Mortgage co’s are still very twitchy about lending criteria etc. Did you state an amount to them or was it just left as ‘some’?
If you have not told them that you were going to pay off some debt then it is a strange clause and I would be on the phone to them to clarify.
Cheers
Danny B