I would look at your overall situation. You need to both be in agreement if you are going to tackle debt.
Have a plan, or take a plan that has worked for many people and use that. Google: Ramsey Baby Steps
Baby Step 1: £1000 starter emergency fund.
You have £900 in an ISA. That could be your emergency fund, if it is instantly accessible. Emergency fund is there to stop you taking out debt when something unexpected happens. £1000 is not very much, it's not meant to be... it is enough to cover a few unexpected events like car tyre damage, washing machine failure, emergency plumber, that sort of thing.
Baby Step 2: List debt smallest to largest, pay minimum on all and pay as much as possible to the smallest until it is gone.
This may not seem mathematically correct. It isn't. It is designed to get you to change your mindset about money. It sets a small goal, you achieve that goal, then you set a bigger goal, achieve that, then set an even bigger goal. If you started with paying off large debt first, it would be like going up a mountain before you have been able to walk in the foothills.
Income - you do not have much coming in, see what you can do to gain more income. A second, third, fourth job. Selling stuff you have at home which you no longer use. Do whatever you can to increase income, so you have money to put towards paying off the debt.
Cash flow management - or budgeting. You need to know where your money is going. You need to be telling your money where to go rather than it just flowing through your fingers. Many bills these days are split in to 12 monthly payments (or 10 such as council tax) to make budgeting easier. Some are variable and thus can be more tricky to budget but you can anticipate something that is coming up in the next month. Use whatever method works for you... pen and paper, a spreadsheet, YNAB app.
So to answer your question, no I would not use the ISA money to payoff the debt. I would use that as an emergency fund, which may mean moving it to an instant access account.