Various companies on here do drive in drive out off the shelf remaps. Have a look in the trader sections on here.
There are also various companies that will do live remaps for you (tailored to your car) but obviously these cost far more.
You can also get as suggested something called and RS Tuner, which is basically a box you plug into your car, then pay and download a off the shelf map onto your laptop and then load it onto the car yourself. Obviously this is the cheapest way, with them coming up second hand on here regularly, but you do need to buy an unlock code. And from the sounds of it your not very experience, and from what I've read they're quite confusing to use.
Whatever you do, being a N/A clio, without any extreme mods, you won't notice any power gains, most report smoother power delivery and removal of the lumpy idle.
Re. Ron 98, that is a type of fuel mix as said. Think Shell V Power / BP ultimate etc. Standard unleaded fuel is around 95 ron iirc.