PN web page serving and domain transfer guidance

[#1]

I want to use the PN web space to serve web pages, but leave the DNS management elsewhere as there are a number of restrictions (e.g. TXT records) on PN's DNS configuration.  Pointing the domain address for web to PN's web pages platforms does not appear to be difficult, but getting the URL to web file space mapping appears to be a bit of a challenge.  Question 111344492 applies.
Whilst looking around the help pages for guidance on this subject, I came across the following...

Quote from: http

4. Full Control Transfers - All other domains (.com .net etc) It costs £15 + VAT (£18.00) to transfer in a non .uk domain. This covers the cost of the transfer and extends the life of the domain by one year. Firstly, ask your domain provider to unlock the domain, provide an EPP code (also known as a transfer or authorisation code) and change the name servers of the domain you wish to transfer to:

Would not following these instructions to the letter result in the domain becoming inaccessible until such time as the PN DNS configurations were built?  Surely the right way to do this is (a) Build your email and web set up in the PlusNet space and (b) Request the transfer, leaving PlusNet to change the NS when PlusNet have built the DNS entries?

[#2]

Yes, it probably is less disruptive to do things like that. It would involve manual intervention at our side though I believe which the system isn't really configured to accommodate

[#3]

Bob,
Thanks for the follow up.  It rather implies that transferring hosting to PlusNET for a live domain will entail some down time.  Though services can be pre-built prior to migration (as I have done for my intended move) during the migration window, there will be no 'populated' name server for the domain, for the time that the user changes the name server on the existing provider's DNS until PlusNET effect transfer and populate their name servers.
Do domain host transfer requests sit in an 'urgent' priority work queue, as the usual 72 hour turn around for tickets would be a real killer here.
Cheers,
Kevin

[#4]

Quote from: Townman

Do domain host transfer requests sit in an 'urgent' priority work queue, as the usual 72 hour turn around for tickets would be a real killer here.

Full transfers initiated via the portal are almost entirely automated I believe so there's no/little manual intervention required. A hosting only transfer is a manual process, but depending on who you speak to, there's nothing stopping us from building the zone records ahead of the NS change in that instance.

[#5]

Bob,
Thank you for clear comprehensive responses.  In short there are things that need thinking about and having done so, there are means to mitigate down time - better than I'd feared!
However for the benefit of anyone thinking of doing what I sought to do - host a web service but keep the name server (DNS) configuration elsewhere - PlusNET system configuration is not amenable to doing that.  A little disappointing but understandable! 
Kevin