I have been where you are and debts are (IMO) one of the worst things that can happen to a marriage, you get bitter, blame is apportioned, you can't sleep for worry and so on.
Time for a completely honest, cards on the table type chat. The chat in which you tell the truth which is- your home is now at risk (even if rented) from your debts and you simply cannot make ends meet at all. That you will get CCJs and even have to go bankrupt if this continues.
So- this means you have to examine every single expense and outgoing and consider how it could be reduced, and how the money you have as a whole could pay back your debts. Basically, and wrongly, you have been borrowing to make up the shortfall in your everyday living expenses (easy to do if you are in the SE for the airports, at a guess). She needs to be putting in pretty much all her pot, pretty much all your pot and it's then doable.
I think you need to get serious and outline the above. It may push her into broaching the stables situation.
You equally need to be realistic about the 'shopping'- if you mean food for a family for a month, it's not £100 at all. It's much more than that (£250-400) depending how much time you have to shop about and go to discount places, if both working this can be a problem. So you need to really understand who pays for what and what this actually costs- not minimise her costs as she may feel you are discounting what she brings to the table.
Hope it works out for you, I think you need to let her know it's crisis time, that your debt repayments have to come out FIRST (after rent, bills) and then you have to manage the rest of the month, even if that means you raid the freezer and shop only in Aldi for the last two weeks of the month (can you tell I have done this?)