The full topic is here and the solution provided by our member 'Marmite toast' is kindly provided below.
Marmite toast wrote:
I found the last bolt stopping me from separating the gearbox from engine which was hidden by a bit of exhaust. I had good intentions of documenting this job with photos but I got completely covered in oil.
Here's a rough written description of the job.
Disconnect battery and take battery out (various bits of plastic to remove)
Disconnect plugs to all of the electrical bits in in the battery box (there’s cable ties clipped in all over the place to free).
Remove battery box (2 screws then pull box forwards off then tabs then wrestle out upwards)
Disconnect gear selector links off the ball joints (by squeezing the white tabs together on their ends)
Unplug the reversing switch off the gearbox and unbolt the earth from the gearbox.
Loosen wheel nuts
Jack car up
Remove wheels and put under car for safety
Drain gearbox (8mm square key needed)
Disconnect hub from bottom ball joints (by undoing the nut and bolt in hub carrier and removing before separating hub carrier from bottom ball joint with force such as hammering a wedge separator between them whilst taking care not to damage rubber gaiter on ball joint)
Remove drive shafts (undo the nut in the centre of the hub, slide splined end out of the hub and carefully pull drive shafts out of the gearbox)
Unbolt the clutch slave cylinder and pipe support nearest the cylinder (tuck it somewhere out of the way)
Take off the exhaust downpipe cat box from the engine (removing the insulation cladding front part then unclipping the box at top and bottom then unbolting the 2 side supports then removing this and the back insulation/cladding)
Remove the gear link cables from their support bracket (lift white plastic ball up to allow them to slide out)
Take off starter motor (There’s 3 Allen headed long bolts to remove 2 going from engine to gearbox direction and one the opposite, there’s also a bracket for the gear link cables which bolts over the starter to remove which has 2 bolts in, tuck starter motor out of the way)
Remove the rear gearbox/engine mount (2 bolts)
Undo bolts holding engine and gearbox bell mouth together (support engine either from above or below and independently support gearbox)
Undo the inner wheel arch plastic to make space for the gearbox to come out.
Remove gearbox/engine support on gearbox side (5 bolts in total, take care that the engine and gearbox are supported by something else)
Separate gearbox from engine (I slowly levered them apart from the gap left where the starter motor was removed)
Lower gearbox out of the car (and remove clutch fork/bearing).
Remove old pressure plate/clutch off the flywheel (star drive bolts)
If you get this far you can figure out putting it back together

The full clutch kit is available here (on EuroCarParts), just enter your reg or year and model for the correct kit for your C3.