As a solicitor I (or any of my legal colleagues) can generally certify copy documents. But the CAA is not interested in that.
I emailed the chap who does our syndicate checkouts/revalidations etc. and post his response below in case others have the same question:
"I am head of an RF (Registered Facility).
ATO is a new EASA term so to be pedantic NO I am not an ATO However.......
Registered Facilities have a couple of years to become ATO's during the transition period
If you ask the CAA you will most likely get a lowest common denominator answer of NO "Must be an ATO"
Common sense would mean that head of RF can sign off during transition period so I am happy to sign it and get you to post it and see if new licence appears."