Furthermore if you would like to get emails on your sever delete this two records:
mx0 - 212.xx.xxx.xxx
mx1 - mx0.123-reg.co.uk
and create your own MX in this format:
plus create following record:
mail CNAME www.mydomain.servehttp.com
(You do not have to do that if you have record
@ CNAME www.mydomain.servehttp.com
as this is so called 'willd' record substituting for any other records.
To explain it further DNS rules ask for MX records to point to A records. However that shortcut above should work even if this is not exactly 'clean')
Remember, if you'll not use your own emails, you'll have to pay to 123reg for email services and set your emails with them.
As I can see your in UK. Depending on your requirements, I can help you with your hosting demands (I am preparing few Virtual Servers in London, all with installed and set ISPConfig on them with optional support for ISPConfig and each of them at least with 3 IP adresses - depends on size of VPS) If you are interested, send PM.