In menu >> system >> setup >> tuner config >> tuner A...
Set up Tuner type == DVB-C. Select your correct VM cable region and Network ID. Save.
Re-open same tuner. Set up as tuner type == DVB-S. If you just have Astra 28.2E set up as Simple, SIngle, 28.2E. Save.
To scan for channels go to ABM, (In menu >> system >> setup >> AutoBouquetsMaker >> Providers). Select Sky UK, Area == your location + Custom. Select Virgin UK, Area == your Virgin Net ID. Press GREEN twice to start scan.
If you don't know your Network ID post back with your location and someone should be able to point you in the right direction.