I sent this (not my entire email):
My understanding is that the notice period is two months. As today is the 4th of May and a bank holiday, I appreciate this may not be picked up until tomorrow, the 5th of May. However, I wanted to ask whether my landlord would be willing to accept my notice as running from the 1st of May, with the tenancy ending on the 30th of June.
I am asking because I have suddenly lost a significant amount of income and I am no longer in a position to afford the rent beyond the next two months. I wanted to be upfront about this as early as possible so that there is as much time as possible to make arrangements.
They responded:
We can confirm under the new law you can give notice to quit in relation to the property.
However, it must end on a rent due date and your rent due date is the 1st Month therefore your end date would be the 31st July.
I know it's not by the book but it's an emergency. I literally can't afford it. The rent is astronomical. So wondering if there's a way to negotiate. I've never had any direct contact with my landlord and I don't think I'm able to. Any helpful insight here would be most appreciated.