You seriously rang the police to ask if you could work?
Words fail me!
I'm sure with all the stuff they're dealing with they really appreciated you wasting their time with that!
Here is the official policy from Gov.uk :
https://www.gov.uk/government/publications/full-guidance-on-staying-at-home-and-away-from-others/full-guidance-on-staying-at-home-and-away-from-others1. Staying at home
You should only leave the house for one of four reasons:
Shopping for basic necessities, for example food and medicine, which must be as infrequent as possible.
One form of exercise a day, for example a run, walk, or cycle - alone or with members of your household.
Any medical need, or to provide care or to help a vulnerable person.
Travelling to and from work, but only where this absolutely cannot be done from home.--
Correct me if I'm wrong, but window cleaning is a job that 'absolutely cannot be done from home' is it not?
The guidance really couldn't be clearer.
If you're that worried, just print out the page from the link above, and if you're challenged by a doogooder or busybody while you're out, just show them this.