Sorry if I now go around in circles on this but...
If an employer has more than 5 employees a written record etc. must be made. So, if those people are carrying out work (albeit on their own) even remotely, risks and safegaurds i.e. the significant findings, must be identified and informed upon. This could then include some method of checking in/out (by phone or other means) and of checking on that person if a report time is missed?
As for posts 10 & 11, I understood that he responsible person must take into account person visiting or nearby their building, so identifying your problems of getting public to leavehas to be dealt with.
Excuse the pun, but, even in places of religious meeting a service is being supplied to a customer.