Our company supports major essential services, so we have obtained "Essential Services" letters from our clients.
I have 3 so far, all signed by directors,etc - customer staff with Authority
If your customer cannot provide an "essential services" memorandum, don't visit !!
Also been advised to carry our contractor ID cards that have been issued to us by other major govt depts (ADHB, etc).
Of course, remote access trumps all 🚳