Virgin Media don't do FTTC. They do HFC (most areas of the country), in some brand new areas they have built FTTP and run it as RFoG so they can carry on using the same DOCSIS equipment, converting it to coax at the property edge, incidentally making this service inferior to Openreach / CityFibre etc which will run as GPON / XGPON using PPPoE as the protocol, DOCSIS has much higher overheads and latency.
This isn't based on the speed at all, my 1Gbps package runs over coax on their HFC plant. Though if VM are running it as FTTP RFoG it is far more reliable than their HFC, and much easier to upgrade capacity.
Statistically speaking you'll be in an HFC area, but you might get lucky. If you are able to get FTTP from Openreach or City Fibre and use real time applications, you'd be better served with them, as DOCSIS results in a lot of jitter. For comparison, my latency to London has dropped from around 20ms to 5ms going from VM DOCSIS to FTTP, and latency to the US has dropped around 20-30ms.