A 2.0 nova will be the same price if you just stuck the reg number in, as it will have gone through the system as a 1.2 or whatever the original engine was.
Try comparethemarket - they were the only comparison site to give me a sensible quotation on my GT4 today. Other than that, pick up the phone and ring round, at least someone on the end of the phone could tell you why the quotes are so high.
SR8 is rated as an E grade postcode area, so thats almost the worst you can get - that explains the crap quotes. I would suggest ditching the clio and getting something as basic as possible, OR looking into security and pass plus. I still think even on a horse and cart you'd be looking at a 4-digit premium.
[edit] I'm assuming the car is standard - if not, remove ALL modifications and start again!