Professional needs room urgently

Hey,
I'm Dan a professional animator from the midlands who just received a job in London and upon accepting the contract (which is for at least 3 months) have been given 3 days to get down ready to start on the 18th of November (no time I know).

Because of this I need a place pretty quickly and cheaply, I have a maximum budget of £420 as mi still on lease for my previous rent with my fiancé (she's staying in the house while I work in London)

I'll be living light for the first month or so, so don't mind smaller spaces and have no dietary hang ups so happy to conform to veggie households if needed.

I'll be a quiet and respectful housemate and probably asleep a lot from the workload of the studio I'm joining, may return to house late but never drunk or rowdy (don't drink alcohol generally, I'm still fun though)

I know it probably seems like a stretch but any help would be fantastic in getting a place to stay while I work.