Treat the light and the fan separately - get the light working then the fan.
The switch with Com/L1/L2 is usually arranged to have permanent Live connected to Com (Common) and the switch connects it to either L1 or L2 as you operate the toggle. The lamp needs Switched Live from either L1 or L2 it really doesn't matter which - this MAY be the Black wire but don't take my word for it....
Bathroom fans are often arranged to have a timed operation and to run-on for a period after the light is switched off - to achieve this the fan requires Live & Neutral to make it work and a connection to Switched Live to let the fan know what's happening with the light.
You do not say if this is a new installation or not - it may be best if it's all too much for you to summon an electrician.
In the UK a new bathroom light is "notifiable" - repair to an existing one is not.
Light switches do not usually have Neutral routed to them - your description of the wires you have seems to be a wire missing - your electrician will sort it out for you.
Good luck...
Peccavi
November 2009
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