hydraulic clutch issues

My wife's Fabia has recently started having issues with the hydraulic clutch, just recently it stopped engaging reverse. I understand the brake and clutch hydraulics are a shared system and there's a possibly of it being a bleed problem, although I do not think this is the case, there has been "NO" major service or maintenance done recently that could cause the problem.

The fluid does seem to be low from the dipstick check but, (mind the ignorance) I'm not able to locate the filler point (reservoir) and I'm under the assumption that fills from the brake reservoir!?

All the forward gears shift ok but, it will not engage reverse.

Any suggestions!

Ciao,

Mark