Ok, finally got around to sorting this.
This was the problem connector, not yet leaking but I think it wouldn't have been long. I spoke to a very helpful guy at TechHose in Hereford, who advised me to buy these....
An 8mm compression coupling and a couple of 6mm brass inserts. I then removed the top of the brake fluid reservoir, covered with a plastic bag and screwed the top back on (this minimises the clutch fluid that leaks out when the pipe gets cut).
I then cut the pipe and removed the damaged connector.
When the pipe was cut, I realised that the inner diameter was smaller than 6mm, so the brass inserts wouldn't fit. I tried to find some 4mm tubing or similar to use but couldn't find anything, and it was the weekend so couldn't go back to TechHose. The wall of the hose is pretty thick hard plastic, so I decided to try and use the compression coupling without an insert. I fitted it, removed the plastic from the clutch resorvour and pumped the clutch pedal a few times. There was a small leak on the coupling. I tightened it up a bit more and no more leaks. I then bled the clutch system (using a Gunson Eazibleed) and replaced with new clutch fluid. All done and seems to be fine.
Hope this helps, no need to replace master and slave cylinders, just a quick fix that costs less than £3.