.thanks for the help everyone!
Its a Fiesta RS1800 zetec engine, with stock alternator.
Will get the battery tested , but first Im going to retest all the stuff like current drain again tomorrow and will update then.

I don't have a clamp meter (yet) to test the dc current with engine running.

I have tightened the alternator belt up as it was a teeny bit slack, but not the problem I'm sure. After more research it could be the alternator is charging but also draining if the diode is faulty?

cheers

ps/ when its charged it turns the car over and it starts instantly. Doesn't seem to be underpowered going on ease of starting anway