Have you changed the Domain Hosting setting to "Other" so you can add your own DNS settings?
With that changed I think you need the following DNS settings
Left field Type Right field
abc.co.uk. A 184.108.40.206
www CNAME abc.co.uk.
Note that you need full stops after the fully qualified domain names in the left and right fields but *not* after the www,
This will mean that HTTP requests to both abc.co.uk and www.abc.co.uk are directed to your static IP.