Just to close this out and hopefully offer some tips to anyone who finds themselves in a similar predicament.
I used an OEM electric Megane2 wing mirror to do, (even if I do say so myself
) an excellent repair!
The Mounting Bracket for the standard Mirror WILL NOT FIT the CC!!!
It needs a signicant amount of plastic cut away including the clips.....Along with removing some plastic from the bottom of the mount/support bracket(To ensure a snug fit)
But with patience, you can easily get it to a correct and almost exact match
I trimmed the plastic to slightly over the required size, then with the window rolled down to use the inner panel as a template, I marked Off the final size of the mount and proceeded to use a heatgun to bend the plastic over to give a trim/lip to the mounting bracket.
After the lip was done, I sanded the inner edges to a uniform smooth finish and mounted the mirror in place (tho unless you choose to add epoxy it will only be held by the centre nut)
I have to say for the total cost of £58/***8364;70 versus the cost of ***8364;125 from
france or of the exhorbitant ***8364;340 I was qouted via Renault for the replacement mirror it is a neat and tidy fix
Thanks for all the advice proffered here folks!