Aspiring DIY mechanic looking for some advice fixing my old mk1 ford ka 2008 on 60k miles for learning purposes.

Problem started when clutch pedal is pressed; a clunking noise comes from the bellhousing which goes away when in gear. I ignored this for about a week and when on the last journey the noise got much louder and it became hard to put it into gear. I then left the car for about 6 months and have now decided to fix it on the weekends.

I believe it is the slave cylinder / throwout bearing. I have pulled the bellhousing off and it appears to have loads of dried fluid the bearing doesn't look too healthy either but im not sure. As I've never experienced this fault before I was wondering if from this photo :

ibb.co/SJPhHdh

Someone who has experience changing clutches can confirm that its the brake fluid that has leaked and dried from the slave cylinder (and it a common fault) or if its something else thats leaked and need changed?

Also while I'm at the clutch I may aswell change it, would it be advisable to do the rear main seal, flywheel or anything else while im there?

Cheers