In Tonbridge you're very local to me - I'm in Tunbridge Wells. What experiences have you got of the dealers round here? I don't use Lifestyle (TW) as their prices seem horrendous.
Also, by how much does your MPG drop in the winter months? At the moment (by my calculations) I'm averaging about 57mpg on a 13 mile daily round commute, whereas in the summer I can get around 63mpg, maybe a little more if I'm very careful and do more longer runs. I notice that my temperature guage doesn't always reach full temperature (4 bars) by the time I get to work when the weather's cold!
Lifestyle is best left alone. I bought my Clio from there when it was still Whitehouse Renault, but the silly bunting around the yard and its aggressive advertising it now employs make it seem too much like a dodgy used car emporium for my liking. I used the parts department once, and was not impressed.
I use Motorline in Maidstone for servicing now, and will get my Clio III from there. I live in Hadlow (on the A26 Maidstone road), so Maidstone is more convenient for me. If it is too much of a hike from Tunbridge Wells, you might try Davis Motors in Sevenoaks, which, I am led to believe, is pretty good.
My economy is about 62-65 mpg right now, but if the temperature drops, it will increase to 57 mpg. I managed 59.7 mpg out of one of the French Clios, by the way.