I forget what offside and nearside is too, I always say drivers side, passenger side.
This thread is about the drivers side as Renault stopped making them, but for some reason they still make the passenger side which is what you need, I would say find out Renaults main dealer price first, then go on Autodoc or ECP etc and see what they charge, they'll say they sell both but passengers side will show up, drivers side won't as they don't exist anymore.
The arch liners are easy to remove and fit, just don't lose the screws as they're tiny.