I'm having some troubles port forwarding on my Virgin Hub 3.0?

See if you can change the port forwarding to match the 192.168.42.x. Maybe what they show is just a default.
Put it another way, if your PC is at 192.168.42.120, there's no way you could access the internet if the router is at 192.168.0.x. Nothing would work on the network…
What is your default gateway? That must be the subnet your PC is in. Things do not match up here, you need to find out why those IP subnets are different.

Are you running another router behind the Virgin Hub? Because if you have a 192.168.42.x address and it has a 192.168.0.X address then some other router has issued your computer's IP! That makes portforwarding almost impossible.

What other devices have you got on your network?

Are you using a PC with Wi-Fi that is running the latest version of Windows 10 (version 1703)? If so, make sure that its Wi-Fi hotspot is disabled. Other devices should be connected directly to the VM router and not to any hotspot provided by a PC.

I would guess that the VM router has an address of 192.168.0.1, so any devices that are connected to it will have addresses between 192.168.0.2 and 192.168.0.254.

If you have a PC acting as a hotspot, then it will be functioning as a router. You would have to be able to port forward through the PC's router as well. I'm not aware that Windows 10 supports this with its hotspot facility.