It's really difficult to tell as the wires are set so far back in the gap where the HU sits which is why I wanted to take something out so I could take a propoer look at the wiring.
The old head unit looks like it could be as old as the car but I can't be sure on that.
The reason I ask re what to take out is that I'm particularly good at taking things apart but not quite so handy when it comes to putting them back together again

So it looks like the glove box is coming out then, hopefully the wiring should be reasonable stright forward from there, it doesn't look like anyone has butchered it at any point, it's only had 3 previous owners and 2 were middle aged women and unlikely to have gone through this process before, let's hope so
Ta for that