could this all be yet another scam ?
Yes, it is, there are no centralized services that have access to any lost Bitcoin. Don't be greedy, and you know yourself that you don't have such funds on the blockchain. They are only triggering your greed to get trap on their scheme.
eg why the £ 325 to Revolute bank... ?
This is possibly their target amount from you and more funds since they are free to ask you for processing fees, withdrawal fees, and all other fees, and yet the fund they are saying won't ever reach your account.
should I just ignore this lady ?
Yes, you should ignore the person.