Moving domain away from Plusnet hosting

[#1]

I have a domain for a support group which is registered through Plusnet (it's a .org.uk domain), I have a website on homepages and forums on ccgi. The organisation has now reached a point where we want to do a total revamp of website and forums (I have a prototype running on PAYH under a different  personal domain), but also we need to take the registration and hosting away from Plusnet so that it can be worked on by people using different ISPs handed on at an appropriate time. The forums are going to be converted from phpBB to SMF, the website is going from static pages to Mambo CMS (using Mambo because of the SMF bridge). It's obviously going to take quite a few stages and I need to work out a plan which will minimise the downtime.
I think an early step would be to do the switch from phpBB to SMF while still on ccgi which can be fairly seamless.
The bit I'm not sure about is moving the domain registration which I think I will need to do before I move the hosting away from Plusnet. When I transfer the domain across to the new registrar, will all the DNS records be removed from Plusnet and will I then have to re-request hosting to get it back?
Finally, any recommendations for a registrar for a .org.uk domain?

[#2]

Quote from: jelv

The bit I'm not sure about is moving the domain registration which I think I will need to do before I move the hosting away from Plusnet. When I transfer the domain across to the new registrar, will all the DNS records be removed from Plusnet and will I then have to re-request hosting to get it back?

That's how I understand it jelv.

[#3]

Quote from: jelv

[Snip] Finally, any recommendations for a registrar for a .org.uk domain?

123-reg and good look with it

[#4]

I use daily for my Domains (20 or so and not had any issues so far) with most hosted elsewhere. The DNS control is very good, are very competitive on price and respond to ticket/email queries quckly.
www.daily.co.uk