For reference if anyones intersted here's what was wrong according to the auto-electrician who looked at it today. . . .
Engine Management / Service Warning is on
valve needed cleaning so perhaps my previous mechanic was less skilled at reading the diagnostics.
Drivers side window doesn't work
Saddly it seems this needs a new motor unit. Very annoying as this was replaced not that long ago under warranty and died about 10 months later and Renault refused to fix.
Airbag light on
Steering wheel makes a horrid clicking noise
This problem was with the switch column. The machanism was faulty and the airbag was damaged and catching on it - hence the noise and warning
Front passenger side indicator not working
This was a dodgy connection
Air con doesn't work
One of the pipes had sheered off and needs replacing and the whole system flushed.
So all in all they weren't really connected and fixable for the bargain price of about £900