So, calling yourself "Wikimedia UK" overemphasizes and misrepresents your relationship to the WMF, and that's discouraged.
Though the organisation will trade under that name! But yes, it shouldn't be its real name.
It will trade under the name *once it has an agreement with WMF* - that's the key point. It's needs another name before then.
(This is also so that, in the event of a chapter dying or going rogue, the Foundation can revoke its trademark licence [WMUK v1 had a 3-month notice period] and assign it to a viable new organisation.)
A 3-month notice period? So the contract between WM UK v1 and WMF wasn't the same one as Delphine has a copy of online (which is for a year and it automatically renewed each year unless someone stops it)? That should make things simpler for the new chapter if the old hasn't finished going through all the bureaucracy of winding up by the time we're ready to sign up with WMF.