So, slightly emotional first session! I attacked the passenger side first and got as far as undoing the hub nut before things got complicated! Had to resort to the angle grinder to slice through the hub nut and the end of the shaft to remove the nut. Once that was done, the lower ball joint was solid, so resorted to removing the lower wishbone. That won me enough space to remove the shaft from the knuckle. Getting the shaft out of the gearbox was also a bit of a mission; I ended up cutting the inner boot, removing the shaft from the inner cup, then rotating the cup whilst tweaking it away from the gearbox with a pry bar. After a couple of rotations with a pry every 30 degrees or so it popped out nicely (that was after my attempt to extract it using rope around the inside of the shaft and a length of scaffold pole as a lever!). Getting the new shaft in was ok; I popped the car in gear, and rotated the shaft whilst pushing gently until it started engaging on the splines. I tapped the shaft home (it was pretty clear from the sound of the tap when it was fully home) then wrestled the knuckle out and onto the outer end of the shaft. It went back together with the usual suspension wrestle, but nothing too serious.
I left the driver's side for another day but on the test drive, the vibration under acceleration was gone!!!
In summary- bit of a pig of a job, but worth it. Hopefully when I do the other side, the clunk will disappear completely (fingers crossed)!!!