Fred - you ask a subjective question - so you may get zillions of different answers....but, as you did ask....
OXFORD VFR COMMS - I've heard it. Not bad, bit deep and boring for my taste - I would think that the same cash spent doing some R/T groundschool with your clubs instructors (or R/T examiner!!) may be equally useful.
Why not round up a bunch of like minded students and get the school to do an evening class with you all - much cheaper then (per person).
RANT - apart from the guy who wrote this software, I am probably it's biggest proponent. I think the programme is absolutely brilliant - best, cheapest, most comprehensive device I can think of for radio navigation practice. Having said that, if you are on lesson 5 of your PPL then it is probably too early for you. This is a very advanced programme - and without being shown how to drive it properly - it would probably lose you.
VFR NAV - not seen it, not in a position to give an educated comment on it.
AUDIO TAPES - probably wouldn't do you any harm - especially if you have a tape player in the car - or a walkman for on the bus. Haven't played the tapes myself - but you are bound to get something out of them. Why not.
SCANNER - not familiar with the model. Depends what it will cost you and what you will be able to hear on from where you are using it. Personally (depending just how much of a price difference) I would consider a transceiver (combined transmitter and receiver - rather than just a receiver). Have it in your flight bag for the days that the aircraft radio lets you down - either through a breakdown or your own fingers getting the switches wrong. ("Finger Trouble" as we call it).
Hope it helps - remember - it's only an OPINION.