Some progress...
New rear springs are fitted and the car is all road legal again.
Finally got my front component speakers in the post this morning - MTX TXC6.1's
Been collecting various wiring kits and an adaptor harness so that the new headunit will still work off the steering wheel controls:
Will be off to get some dynamat in the morning and then getting all this little lot fitted, including the JL Audio sub and amps and some rear speakers.