Having lived in England for 4 years, I was in quite a few homes. Most of what I saw had very small rooms, packed wall to wall with furniture.
If a person were to clean the carpets, it would require a lot of physical moving of heavy furniture in and out of rooms. Your physical abilities would be limited to handle this lifting.
Another problem with cleaning the houses is that most are two levels with tiny little staircases. Lugging the equipment on the stairs would also be problematic.
You could always hire help, but keeping good help is a major issue and you might end up at times with houses to clean and no help at the moment.
I would find another line of work that is more geared to limited physical abilities.