Just an update
Got the polystyrene out of the way and was no problem at all. The tubes gave way and i could get access!
Next disapointment though was the kit I got from newministuff seemed awkward to fit. Got the harness adaptor on ok but the aerial adaptor didnt seem to want to fit
Perhaps its just me. I tried everything and it doesnt seem to wanna go. Gonna try and grab and autoleads cable in the morning from somewhere and try again. In the meantime... no stereo!
Thanks anyway for your earlier advice. Got there in the end. Cables let me down