You are asking a tremendous amount, but not giving enough information ....

Drive Calais to Paris, arriving late afternoon/early evening, spending the evening in a fab french restaurant and visiting Eiffel Tower at night, when it is illuminated! (Restaurant and Hotel suggestions greatly appreciated, looking for something relatively cheap, but also realistic that it is city centre and want something nice that is a bit classy!)

You are asking for a great deal of stress trying to drive in central Paris. I would strongly suggest that you stay somewhere outside Paris and take the train in. The Eiffel tower displays the twinkly light display for five minutes starting on the hour from about 19H00 if memory serves me correctly. If you have a Sat Nav/GPS you might try driving in central Paris but I would not advise it. Why not stay in the area near a RER suburban train line for easy access and parking ... eg Bussy St Georges, near DLP.

http://www.ratp.fr/plan-interactif/

Find a town, then google Chambres d'Hôtes and the name of that town/village. However, you've not mentioned party size and you want a budget holiday so I'd suggest looking at the following chains - Ibis, Etap, Campanile, Hotel Premiere Class, B&Bhotel.

Visit various touristy places, Notre-Dame, Louvre, Catacombes, etc. Travel to Hotel between Paris city centre and Disneyland in the evening. Suggestions again please, I know the drive is not long, but my thoughts are that if we can save money on this hotel, we can look at somehere nicer in Paris for the night before.

Commute in by rail. You do NOT want a car in Paris, nor the parking charges or parking limits linked to it! The Hop On Hop Off bus tours are useful, or get a guided tour from an agency such as Paris Travel Service so that you get an overview before you set off at your own pace. Paris is a VERY big city as regards the centre.

Ditto! But leaving there early evening, and beginnig to make our way back home. I would like to stop at somewhere on the way home to have an overnight break, ideally somewhere we can explore the following day too. Maybe around the WW areas, so we can visit the trenches and gravestones. Can anyone suggest a B&B, tradional, family run, etc.

You are probably looking at somewhere close to the WW1 battlefields, but with something nice to see in a city as well. My suggestion would be Amiens with its cathedral and lovely watergardens (hortillonages) that can be visited by boat. The book also appears in Sebastian Faulkes novel 'Birdsong' if you've read that and was the birthplace of Jules Verne.

Google 'World War 1 battlegrounds in Picardy' and 'Amiens' for further info. You could also google 'Amiens Tourist Office' and see what they offer under HEBERGEMENT (accommodation). You might be interested in Pensions and Chambres d'Hôtes.

However, I must say that I think you will find it very hard to do this on a 'budget', especially if you want to spend

the evening in a fab french restaurant

in Paris.

I second Amiens as a place for your last night. However when we were there last Summer we found it hard to find a 'good' restaurant in the sense that there appeared to be no middle ground, they were either tremendously expensive full monty type places or cheap and cheerful cafe type places with loud music. We ended up in an Italian restaurant!!

I would also go along with the 'don't drive in Paris advice. Driving through it is bad enough. The metro system is very good and will get you to most of the tourist places easily.