Barmaid, this is a long journey for someone who has not driven abroad, and typically of me I'm going to suggest you take a lovely train ride instead so you can enjoy the view and not arrive frazzled, with the prospect looming of having to drive back. You will be driving a long distance and the last leg is mountainous.
You can get a daytime or an overnight train from Paris to Bologna or Florence then a local train to wherever is nearest -Lucca?
http://www.seat61.com/Italy.htm#Florence
The continental trains are lovely, not at all like travelling by train in the UK
If you do not live in the London area, I would recommend getting a cheap flight to somewhere like Pisa and again taking advantage of the excellent rail network to get to your destination.