Golf 1.8 Mk III SE (same as GL.. ADZ engine) not starting.. help!!

This has happened at a bad time.. moving house.. no money...my trusty
1.8 Golf isn't starting...

Running great until yesterday, returned to car after using in the day,
it turned over but didn't start normally, slowly spluttered to life.
Went to garage topped up, car wouldn't start at all. Called out
recovery guy and of course when he arrives it splutters to life again,
cleans dizzy cap, arm rotor, car starts "as normal" we tried it
again.. so off I go. Drove as normal once started

Today used car in morning was fine. Then same problem, spluttered to
life and sounding horrible, slowly got up to normal idle and then
returned to normal/ drove as normal. Now at home the problem is
present all the time. Called out recovery guy he pulled a plug the
spark was weak, cleaned dizzy, sprayed everything with W40, check this
-check that.. now there's no spark any more. He reckons a) coil was on
last legs is now dead b) change sparks + dizzy + rotor arm c) get it
surviced asap. He was also suspicious of iginition, but felt most
likely coil, so have one on order... but before I start changing all
these parts, would appreciate some input..

Other things noticed is light metallic tinkling at 2,5k-3k.. which I
understand to be misfiring.. but it's been this way for ages. Also the
oil was down, I lose very little oil normally.. so that may be
unusual, not sure. Occasionally found the key not to work, just
nothing, requiring a second go, running fine after...

I have removed old coil, but am going off this guys word, and would
like to know if it sounds like anything else. Any input, really,,
would be appreciated..

As a novice, am I safe to change sparks and dizzy parts?? I hear you
can overtighten sparks, and distributor itself might want alignment
after being messed with..