I thought about that one too - you'll find you can ONLY get acme.uk IF you already own acme.co.uk (which is taken).
I'll check that later, as I bought psyclist.uk without owning the .co.uk version.
In the pre-launch period there was a restriction on needing to own the .co.uk version, but there are no restrictions now in place. The following is on 123-reg.co.uk website:
"The .uk domain is available on a first come, first served basis. This applies to all such situations, with no exceptions."
My preference would be acme.uk - it as simple as it can be - .uk is the new black
(my bold)
I'm guessing that only applies where the corresponding .co.uk isn't already registered.
123-reg.co.uk shows acme.uk as unavailable.
tsohost.co.uk shows acme.uk as available, but if you try to buy it you are confronted with a screen that says
"acme.uk
Great choice, but are you eligible?
acme.uk has been reserved and can only be
registered by the current owner of acme.co.uk
For the registration of acme.uk to be successful the contact name, email &
address you use must exactly match the owner contact details of acme.co.uk.
If you're not the owner of acme.co.uk please go back and search again."