The reason we could all record one channel and watch another in the days of analogue TVs and VHS recorders was that we had TWO TV tuners.
One was in the TV (of course) and the other was in the VHS recorder.
So you need to replicate that situation with digital tuners and have two digital tuners.
So if you by a DVD recorder with a digital tuner in it that is one tuner.
You then need another tuner, either a stand alone freeview digital tuner, or one built into your TV.
So the answer to your main question is YES, you will be able to record one channel while watching another if your have two "freeview" (digital) tuners.
It would help if your TV had two scart sockets in it, one for the Freeview tuner, the other for the DVD recorder.
If your TV has not got two scart sockets then connecting it all up could be a bit difficult.