For anyone interested i took the meggy to Renault today and had it checked.
The mechanics report is as follows:
"Carried out clip test on electric roof, several faults stored. clear fault memory check operation several times found working ok. check NSF roof switch & lubricate
carry out road test, message came up on dash roof mech and service light then went out. carry out clip test 5 permanent faults occuring when cornering right.
strip interior and check switches, connections and inspect wiring loom for chaffing. restest vehcile several times unable to reproduce fault again. rebuild and restest several times, all okay"
This may make sense to any mechanics out threre, if so please decipher for me (would love to know what a clip test is)
anyway upshot is the roof seems to be working fine.
The prob is definately electrical and not mechanical but requires the whole wiring/roof mechanism to be checked.
Total cost of work was £180. This is basically 2 hours of labour involved in checking all the wiring etc. (Not bad considering i charge that per hour in my job).
My advice is that if your car develops this fault get it to Renault asap or it may get worse.
Any views/comments?