just been quoted a stupid amount from the garage and desperately need to have a go myself but im not sure whats involved

I just replaced one.
1. Moved the rack boots out of the way.
2. bent/broke off the locking tabs on both sides.
3. Unscrewed the tie rod ends from the rack. (left the hang from the wheel)
4. Removed the banjo bolts from the rack hydrilic llines.
5. removed the 2 bolts holding the rack to the crossmember.
6. Had to bend the crossmember mounting tabs down in-order remove the rack.
Replace in revierse order. Add fluid start the car and rotate the steering wheel from one end to the other to prime the pump.

Good Luck
Ron