No 1st and 2nd Gear

I recently bought a 1983 1.1 Golf C. On the drive home the gear change seemed a little clunky. I put this down to the gear linkage being worn or needed a bit of adjustment. Car sat for a couple of days and now I can’t get it into 1^st or 2nd gear. 3^rd, 4^th and reverse engage OK so I’m assuming the clutch is OK. It does appear to be losing gearbox oil as there is a puddle on the passenger side and the bottom of the casing it wet with oil

Has anyone experienced this? Would I get this issue if the gearbox oil is low?

Attached are a couple of pictures of where the gearbox is wet with oil. I assume the sensor is the reverse light switch (not sure the reverse light is working). The torx bolt is on the front of the gearbox casing, I’m not sure what exactly this is for

I would suggest that your first course of action is to replace the worn bushings and link's.  I have had the links when worn occasionally POP off the selectros and
would lose a gear or three.  

Hear is a linkage adjustment guide, and It Probably wouldn't hurt to look at and replace the engine mounts as a bad right side and rear mount can cause shifting issues as well

Guide:
https://www.cabby-info.com/files/transmission/ShifterLinkageGuide_5speed.pdf