A DVD recorder does have a TV tuner (like a VHS recorder does) and you can record from those channels.
But the TV tuner in your DVD recorder may only be analogue, so you could only record the 5 main channels (it may be a freeview tuner though).
If you want to record from the Virgin box then you need to connect the Virgin box to the DVD recorder by a scart lead.
Then add another scart lead from the DVD recorder to the TV.
So the Virgin signal goes IN the DVD recorder, then OUT again to the TV.
You then need to set the DVD recorder "channel" so it is "listening in" to the Scart socket at the back.
On my Panasonic I have to press the "Input Select" button on the remote control to change the "channel" on the DVD recorder to be A1 or A2 (depending which scart socket you are using). On mine it is A2.
Once you have done that whatever is on the Virgin box should go through the DVD recorder and be shown on the TV.
If you then put a DVD disk in and press Record on the DVD recorder it should record what is being shown on TV.
I have to say the Panasonic guide for DVD recorders are AWFUL (I have two).
Good luck !!