I have the exact same issue. I have been provided with a self install kit but have no Virgin Media wall socket. I can't find any way of organising a technician now through the website help centre. Please can someone from Virgin Media respond to me and help me to book an appointment? Thanks in advance.
Call the pre-installation and delivery team on 0800 052 1734
Have you checked to make sure there is no other kind of connection? Sometimes there is no wall box, just a trailing cable. The cable could be hidden within, or behind, furniture. Occasionally only a very short stub of wire is left behind often hidden within a blanked-off fitting. The wall box may be branded with the logos of an old cable TV company (not VM). Past occupiers of your property may have removed the cable and sometimes they are removed by other installers, such as satellite TV techs.
If you have a plastic omnibox outside on the wall (where the VM cable comes in from the street) see if you can trace any wires from that into your home.
If no luck, call the number above for a tech installation.