So, how to condense all this. Well, probably not that easy without losing much of the detail, and as the saying goes: "The Devil is in the detail."
1. Autoroutes have, generally speaking a higher average speed than the RN (Route National) and RD (Route Departmental) but also have tolls which could cost about (can't remember how much we paid now) €75-120 each way. But, on days where there is very heavy traffic it can take 15 minutes a time to get through some toll bars. Plus the levels of traffic can add another hour to the journey times.
2. If you are young enough to stand 10-12 hour days covering 650 or so miles then the trip should be easily completed in two days, although I know a chap in his 80s who drives from Manchester to his family in Genoa in Italy in one go. He loads the car up with fuel and luggage and then puts a small cardboard box on the passenger seat containing food and drink. That way the only time he stops is for the tunnel and to fill his tank and empty his bladder. However, if you are not used to long journeys, beware of tiredness bringing on flawed judgement and even halucinations.
3. My recommendation would be to try and make the journey part of the holiday. For instance, the next time we drive to Nice we will drive to Reims and stay in the Campanile at Reims sud, Murigny. At €75 per night it's not the cheapest in the company, but having got there late afternoon, you could have a shower then drive into the city centre for a bite to eat near the Cathedral which will bring the pace of the day down nice and easy. Failing that, about 15 miles south of that hotel is the Campanile at Epernay (Dizy). Epernay is the home of champagne and driving into the town centre for some nosh and a drink is given an almost surreal sensation as you pass the head offices of firms like Moet & Chandon, Lanson and many others. The next day we'd drive down to Dijon which is largely medieval and the Campanile (yet again) at Dijon Nord is the one we stayed at. It is in an industrial area so if the hotel's restaurant has closed, you have no choice but to go into the city centre. One factor all three of the above mentioned hotels have in common is that they are within a few hundred yards of a large supermarket, an Intermarche, Carrefour or SuperU.
4. That's worth knowing because in all 3 cases they have a filling station which can cut €0.20 per litre off your petrol bill. In a reasonably large car, like the Alfa 156, that can mean almost £10 per tankful and as you will probably need 5-6 tanks to make the journey that can be a useful saving. On the subject of fuel, diesel is considerably cheaper in France than sans plomb, somewhere between €0.10 and 0.15 per litre. The other thing worth bearing in mind is that almost all 95 Regular petrol on sale over there is E10, or in other words 10% Ethanol. This shouldn't be a problem if your car was made after 1999 and indeed the 2001 registered 156 seemed to drink it quite comfortably, but if you are taking an older car it would be worth checking that it's ok to fill it with that kind of fuel.
5. Although you can use cards to pay for the Autoroute, it's worth finding out at what exchange rate they will charge you. If they will only give you €1 to the £ instead of the €1.18 you can get on the high street it could cost you another £20 to make the journey. If you pay by debit card there could be a handling charge as well. Personally I favour cash. Take a good hard look at the symbols over the lanes at the peage to make sure you don't end up in the wrong queue.
6. Don't forget to take the necessary items like a warning tri-angle, flouresent hi-vis jackets (1 per occupant), GB sticker, spare bulb kit and, ideally a First Aid kit, although we forgot to take one. Perhaps the most obvious is headlamp beam deflectors. This is very important because along with the GB sticker it's very obvious and could give the Gendarmes a good reason to stop you which would then allow them to check whether you have all the other bits and pieces as well. If you have number plates with the little blue panel on the left with GB printed on it, you won't need the GB plate.
7. Talk to your insurance broker and have a look at your policy. If it has a short statement (in several languages) saying that you are insured to drive in that country in accordance with minimum insurance requirements then you should be alright, but whatever you do, take the original policy document with you. You will also need the (original) registration document, or if it's a firm's vehicle or leased, a letter from the owner saying that you have permission to take the car outside the UK and a current MOT certificate if appropriate.
8. Although I've never needed it, every time I've taken the car abroad I've taken out AA European Breakdown cover. Although other organisations provide this kind of cover, I've always used the AA because they have their own call centre in France manned by English speaking staff which, let's face it, if you need that kind of service, you don't want to get someone who you can't really understand and who doesn't really have the faintest idea what the hell you're on about.
9. DRIVE ON THE RIGHT!! I know that sounds pretty stupid, but every single time I've driven in France over a period of about 30 years, I've turned onto the wrong side of the road on one occasion. Never more than once, but one time is all you need to die.
Bonne Voyage
mes amis