Great stuff!
I'll give you a quick run through of how to register your nameservers with 123 because that's who I use for my domain registrar. I'd imagine that you've instructed 123 to keep your existing dns6.com nameservers for the time being?? This should ensure that your web site hosting still works as it does now.
Anyway once you have the web site hosting files copied over to EUK and you have a working version on the new
VPS Hosting all you need to do is setup your personal nameservers in CPanel (as I mentioned before) and then you're ready to update the 123 control panel with YOUR nameservers as follows:-
1. In the domain control panel click on the Change Nameservers link.
2. Enter ns1.sound-designs.co.uk and ns2.sound-designs.co.uk into the first two nameserver textboxes.
The thing to note here is that because the domain name of the nameservers you have just entered is the same as YOUR domain, 123 knows that these are YOUR personal nameservers. It therefore has to know the IP addresses of the two nameservers so that any internet query for ns1.sound-designs.co.uk or ns2.sound-designs.co.uk will resolve to your
VPS Hosting.
You will be prompted to enter the IP addresses and in theory that's it!! All done!
Now any query for sound-designs.co.uk will need to query ns1.sound-designs.co.uk. The IP address of this nameserver is held by 123-reg so the lookup now knows to head on over to your
VPS Hosting to find the nameserver. Once there your nameserver service (called BIND) says "yes the IP address of sound-designs.co.uk is xx.yy.zz.xx. Obviously in this case the IP address of your web site hosting will be the same as the IP of the ns1 nameserver but that's not important. The query will now know the IP address of your
website hosting and SHOULD be able to find it!
Let us know how you get on...