Well, just thought I'd bring a conclusion to all this. Hopefully it'll be of use to others as well.

Last night I did the following:

Made up new loom to go from the rear connector to the head unit and ran this the full length of the car.

Made up FAKRA aerial cable using various adaptors and ran this to the front of the car.

Those two jobs alone probably took 3 hours.

I checked the wiring worked with my new CD player and then moved on to adding blue tooth and an aux kit.

The parrot Blue tooth was a doddle and links perfectly with my iphone with no visible parts at all. Just the controller hidden away in the glove box. The rest of the time, the steering wheel gives all the functionality you could need.

The aux in was easy too. I installed the socket in the glove box but I may move it to the switch panel between the cubby holes. Not quite decided yet. Something really cool about the aux working with an i-phone and bluetooth is that you can use voice commands to play tracks using the phone steering wheel button. So I can hide the iphone in the glove box and have almost full control over it.

Anyway spent another hour or so tidying everything up.

Really pleased with the results other than two things.

Lights on illumination isn't working on the head unit so the buttons can't be seen at night. Need to check my connections.

The other thing is that I had thought that the CD palyer would show OBC information like my old nav unit did but that doesn't seem to be the case. I can live with that.

Huge thanks to Big Bob for his guidance on this. I've achieved exactly what I set out to. I also have a nice big pile of bits to sell on.