Intermittently sticking clutch

So I was driving home from work yesterday (hot day, 33 degrees), when my 92 n/a started having clutch issues.
 
It came on so suddenly, my clutch bite point went from a noticeable distance up, to 1/2 an inch. I had to pump the clutch to change gears a few times. It was on and off - for a few minutes it was normal, and then next thing, each change was a struggle.
 
I left the car overnight and drove it again this morning - all was good for about 25 minutes of the trip, but then I had another short stick - it was just the one change today though, and then all was well again. 
 
It almost seems to be heat related.
 
 
I was planning on checking the clutch master / slave cylinders for leaks tonight, and maybe bleeding the system. Dumb question: Where will I find the master cylinder on a 92 sw20? Is it visible from above, or is it an underneath job? I've got a lack of space at home for getting under the car

Thanks for that.
Had a quick look last night, and the fluid level was a little bit low (maybe, 1.5cm from the max level)...
 
I topped it up, and haven't had an issue since.
I think I'll bleed it over the weekend and see how I go.
 
Anyone else had a similar problem?

Just a hint on bleeding the clutch.
If the fluid has turned black it's best to flush it all out, and refill with fresh fluid.
 
And as s I once found out when using a suction bleeder, that tiny reservoir is very easy to run dry, so watch the level closely.
If it runs dry, the pedal will go straight to the floor and you'll have to start all over again, a PITA.
 
 
 

Thanks for all the advise.
 
Ended up being a master cylinder leaking internally.
Ran a seal kit through it and it's back to normal :)