How To Get Registered For A PHD To Be Done By Correspondence?

You will need to look around for universities and Colleges that offer PhD by correspondance.
Many institutions do offer post graduate courses by corresponadance but not all offer PhD studies.

The best way to go about this is to make the desison on what your research will be and how much time and money you have to spend on your studies. Onece you've done this search for an institution which offers the subject you want. You may find this a  limiting factor and have to re-assess what you are willin to research.

You will not receive any financial help for this kind of degree if you are in the UK and must be able either to self -fund or get sponsorship. Correspondence degrees tend to be very expensive although some paces do allow payment over an agreed time by installment. It's helpful to get a list of places you think could be helpful and telephone the department relevent to you in order to get good advice.