Thank you for your question and patience, I’m Tom and I’ll try to help you.
Obviously, you would remain liable to the landlord even if your verbal agreement with your girlfriend were legally binding with her. This is because any contract with your girlfriend is completely separate to your tenancy agreement.
This means that the landlord would be able to sue you if there are rent arrears and this will not change. So, however you resolve the issue with your girlfriend you need to ensure that the rent on the tenancy keeps getting paid.
A verbal agreement with your girlfriend that she would be responsible for the rent is capable of being legally binding provided that you both understood that it would be legally binding when you agreed it.
Therefore, you could sue her if she did not pay the rent to recover such damages as non-payment of rent causes you as a result of the landlord taking enforcement action.
You can foresee though that your girlfriend may dispute the statement or dispute that the verbal agreement was intended to be legally binding. If this happens then it’s going to simply be down to the judge to determine as best as they can whether it was intended to be legally binding.
My view is that if she resists paying all of the rent then you should posture strongly that you will sue in the hope that you can negotiate a settlement of some sort. Litigating with no evidence on a “he said, she said” basis is very uncertain and likely to become protracted.
My goal is to provide you with a good service. If you feel you have received anything less, please reply back as I am happy to address follow-up issues specifically relating to your question.