For budget London accommodation I was impressed with the Forest Gate Hotel.
Pros: quiet location, easy walking distance to the tube (Olympic park 2stops away), affordable (for London prices), clean sheets, comfy bed, fridge, microwave, tea and coffee in room. Fire doors and a solid door lock.
Shared toilet and showers but they are clean enough, a decent size and will good locks on the door. Staff are friendly and breakfast was simple but a bonus the next day, and was cooked fresh.
Cons: it's an old building and it isn't freshly painted and high spec. If you're looking for luxury, you'll have to pay the cost. But it doesn't detract from this being a solid option for somewhere to sleep well for a couple of nights.
I'd recommend it here and I'd stay again.