Charleygirl has a medical background.
I think that thorough hand washing and sensible precautions should be practiced.
Sadly, it is impossible to create a germ free environment, we just have to do the best we can.
I think the suggestions 're going for a drive etc seem sensible. Perhaps ask the cleaner to wipe down surfaces with a bleach or disinfectant solution (providing of course you have or can get either) will actually mean that the house is "cleaner" than it would be under normal circumstances.
If the OP and DH do not come into contact with the cleaner or her child, it meets the advice given on social distancing and by doing a wipe down of the hard surfaces with the right products, could actually benefit.