Can anyone recommend an inexpensive hotel in london ok to use for photoshoot?

You've got a few choices but are limited by price.
Firstly Premier Inn, Holiday Inn and Travel Lodge all offer reasonably priced accommodation, the problem is they look like what they are - pedestrian hotel accommodation.
There are a load of hotels in the Bayswater area which are cheap but most are pretty grim and very tight for space.
London is a very expensive place to live, work and stay and most models won't have room in their places (I've advertised for this repeatedly and got no-where) so you are going to struggle.
I travel a fair bit and choose to stay in apartments through AirBnb and one of my criteria is "does this work for photoshoots?" Using this you can find plenty of great accommodation in London which is much better value and of course you have unique settings, plus if you are prepared to be in the underground zone 2 you get more for your money and it's still quick and easy into the centre.
Good luck