Does your daughter ever return the compliment, that is, does she invite you and your husband to her home for a meal, an evening together, a chat?
It sounds as though she is taking you absolutely for granted, somewhere to go and offload her child because she doesn't want to be alone with her, or cook their evening meal.
You have to make it clear to her this is not acceptable and suggest she comes, say, a maximum of twice a week. The fact you are working is enough, also the fact that when she doesn't have her child you don't see her.
Most importantly, she must learn to take responsibility for her child.
To think that London, or anywhere else for that matter, does not belong to any one demographic