I just want to confirm what i've seen in other threads for other cars.
I have a 93 Audi 80 and the other night the fans were unsuccessful in clearing the windscreen adequately.
Didn't think anything of it, next day steam came through the vents like a puff of smoke and as I understand it I need a new heater core ?

First, is this a big job - i've been told all-day job,
Second, could this have something to do with the fact that my coolant levels have been dropping quite quickly and i've needed to keep topping it up quite regularly ? When I took it to someone for a quick look, they could not find anything obvious and I haven't had time to take it in for a thorough check.

Thanks

Job is big. Well not really, just a lot of crap in the way.
you can do the heater job your self. I wrote a guide on how to. go to my link.
the coolant has to go somewhere, so it goes out the heater core. in any case, put a bypass to the heater core. so you wont have to add any more liquid.