It was mentioned at the top, but I have bad experience with coilovers, makes the ride very unforgiving.... so will be leaving this to last. SC kit sounds more entertaining than suspension
You probably bought / experienced cheap coilovers (Racelands, TA Technix, etc..). If it was me, coilovers/3D fast road alignment would pretty much be at the top of my list. Go for Meister R, Gaz, BC etc, which can be picked up for circa £300 2nd hand on the forum.
Tried BCs twice, dont like them... For me decent suspension is going to cost more than the car