The sporty clios all have the same seats they are just covered in different materials.
I have just swapped my clio 1.4 s seats for 172 seats (silver stiching 2002 type) and the visual difference is definitly worth it.
With regard to the airbag and service light, no you cannot connect the new seats up to the existing wiring loom. Theyre totally different. To get rid of the lights you have to remove the dash and wrap each bulb with black electrical tape. Replace the dash and youd be none the wiser.
Lastly, I didnt find 172 interiors that hard to find. You can buy a mag similar to autotrader just showing companies breaking cars. Its called something like autosalvage, got mine in WHSmiths. Your guaranteed to find a few 172s being broken out of the 1000s of companies listed. As far as price goes, Cliospares offered me an interior for £450 which I had to collect, but I managed to source a mint sub 5000 mile interior for £330 +£40 delivery.
To make my modding experience even better ive just sold my old interior for a tidy little sum which is buying a nice set of mats.
Any questions please feel free to ask.
Simon