If the flat is worth GBP25,000 and there are debts of GBP25,000, then the estate is indeed insolvent.
If that is the case, and that is no money left after the payment of funeral expenses, then the debts die with your stepmother.
The only time this would be worth “saving” would be the price that could be achieved in respect of the sale of the property was more than the GBP25,000 debts.
If you really can’t be bothered and want to walk away from this, then you are at liberty to do so and let the landlord foreclose on the lease and let the debt die away.
You’re concerned about personal liability, then provided you have not taken any money from the estate, neither you nor any of the other beneficiaries or trustees or executors have any liability.
There is no need to worry about that.
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