It might seem a strange choice for me to suggest to you - especially if you live in London, rather than are just visiting - but give the Indian YMCA a chance, and you'll see why I recommend it so highly.
It is not actually anything to do with the venue itself, though I am sure it is more than acceptable for people's needs who stay there. It is not actually to do with the location - though it is in Fitzroy Square, a fine looking area very close to Tottenham Court Road and the main thoroughfares of Euston and Kings Cross. It does have everything to do with their wonderfully affordable dining room.
Now, you don't need to be a resident of the YMCA in order to be able to use the dining room, it is available to all (though breakfast and lunch are included in the room tariff for residents, and their is a priority obviously for those who are staying there). You can attend for dinner, and their is a take-away service available too. The dining room is canteen style, and their are a limited amount of choices between vegetarian and non-vegetarian dishes, with sides such as poppadums and pickles, and onion bhajis. Still not sure why I'm suggesting this? Well, it is all about quality and price.
The food is as close to home-made as you can get without actually going to somebody's house to eat, and the most important thing of all - it is such incredibly good value, you won't actually believe the prices. Seriously. Depending on what you have, it is actually possible to have a three-course meal for well under a tenner, and a decent feed will see you only just top this. So take your tray, join the queue, and enjoy the tasty delights this very cheap and very cheerful place has to offer - no frills as never been better value than this.