Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
The UK has no gifts tax regime so your mother can transfer money to your account in England as often as she likes and a much as she likes. The only thing is that you should warn your bank of the incoming funds and their source to preclude any money laundering inquiries a large transfer might attract.
I suggest that you contact the bank to explain the situation of your father's demise and adjust the account to only two joint holders.
All these activities are outside the scope of UK taxation.
I do hope that I have been able to set your mind at rest on this matter.
Thank you for your support.