Just to add my two cents - if the n/s/f tyre is wearing on the inside edge then I reckon you need a new steering idler - £30 off fleabay and about an hour to replace.
Rear springs - I got mine from buypartsby, at £35 each (KYB RJ6227, but they were rear springs for a facelift saloon with self levelling suspension). Took me about six hours to fit, but that was my first crack at doing them (following Marks DTM's guide) and included popping out to buy spring compressors halfway through (you WILL need them!).
Parts are cheap, the work is easy to do, and you have a FREE car! Nice one, mate! 
I dropped the diff slightly. The springs will then go in without compression.
With the car on axle stands, put a jack underneath the diff for support and to control the lowering and raising. If I remember right, there are four bolts securing the diff and something rings a bell about disconnecting abs leads. If all goes to plan, shocks and springs should be comfortably done in an hour and a half.
