Unfortunately that is probably about right for a garage, even a non-dealership would be a similar price and I would normally budget around £300 for a timing belt - cheaper than not doing so and having the head off to replace the valves when the belt goes
On my own car the kit is £80 (for belt and the tensioners which need replacing at the same time) but the book time for the job is 2 and a half hours. With labour rates at £80 per hour and upwards of £100 per hour for some dealerships (in this part of the country at least) the £200 plus parts is probably fairly accurate.
The alternative is to find a good private mechanic, which should cut the labour cost down, but make sure that the work is guaranteed for the normal belt replacement interval. Renault can be a bit funny for tools on some jobs but mechanics can often hire them or may have them anyway if they are working on Renaults regularly.