Welcome to my Mk3 , a 1980 2.0GL with 51k on the clock…

Having picked up this little beauty last weekend as a spare car plaything, I’ve built up a small list of goals that I want to achieve with it;
- Get an M.O.T.
- Give it a full service and learn what all the oily bits are for
- Fix essentials, such as brakes, suspension, rear wiper
- Stop the rust that’s eating away at it and spruce up the bodywork a little
- Get out and have fun in it
I’ve made sure to get this list in first so that six months down the line folks can mercilessly remind me how low I set my sights 
At the moment, my ground rules are that the car must remain moveable with two weeks notice (due to an impending house move), money is an object and the car should stay close-ish to standard (enough to convince my darling girlfriend, at least
).
The main problem I’ve got is that I’ve spent most of the last twenty years throwing the keys to the chap at the garage to deal with any problems, so I’m starting from the position of not really knowing anything. I learnt to gas weld at college (before dropping out after 3 months), but that’s about it. I’ll readily admit that I know stuff all, so please excuse what might at times be some glaringly obvious questions 
Onwards and upwards then. Having checked the basics on the car before setting off, I drove it straight down to the MOT centre to see whether I’d got a lemon or a peach.
Almost, but not quite … failed on wipers, headlight aim and two small holes in the offside sill just level with the front spring hanger.
At least the tester was a nice chap into Morris Minors who happily put it back on the ramps and showed me “how nice and solid it was underneath”. He said he’d want to see it come back with a seam welded patch to the sill – nothing fancy…

On the basis that I’m scuppered without an MOT, I got in touch with a local young surf-dude type via the power of Google and a VW camper forum, and he’s coming round this week to get it sorted.
Whilst waiting for various engine service bits to arrive in stock at the motor factors, I’ve made a start at the rear end and discovered where the previous owner used to keep his fish 

So, first questions that spring to mind are;
- what did the three discs in the wheel well used to be, and are they important, as the Haynes doesn’t hint ?
- what’s the best plan of action for now ? Clean down to bare metal, rust treatment then primer ?
- there’s a couple of small holes arrowed – is the floor double-skinned here or did my scraper hit the top of the petrol tank ?