Hi,
Welcome to Eukhost Family!
You can forward your domain registered at Oneandone.co.uk to your
web hosting account. You will just need to change name servers for that domain.
If you have lost your Welcome email, You will need to mail us at billing [at] eukhost.com from your registered mail id, so that we will reset your password and resend the Welcome email, which will contain your Plesk Control Panel link, Login credentials & Name Server details to be used.