We will be arriving in Ancona from

Just use the Via Michelin route planner, choosing Ancona to Calais and add via Luxembourg.  Route given is good, as it misses most of the French autorotes that are toll roadsOvernight in Switzerland can be expensive, but there is accommodation [Holiday Inn Express] at the Nuenkirch services, just north of Lucern, and about 7 - 8 hours into the journey  [approx 150 swiss francs] Total journey time approx 15+ hrs - so second stay could be in/around Calais [for an early start] - look at Booking.Com or similar for options.Fill up with petrol in Luxembourg - very cheap. If you haven't booked the ferry yet - look at the Shuttle - a bit more expensive, but you would save at least 1, and probably 2, hours off your journey

Because do no try   Ancona >  Como > Basel > Melhouse > Colmar  - Route de Strasbourg  ( here have a very not expensive and  little Hotel  , on the road - front the Colmar  Airport  ) ,https://plus.google.com/photos/photo/105535696897460200056/6576693044430491634HotelF1  Colmar Parc des expositionsthen Nancy , Reims, Calais -  i use this  route, and hotel, a few years ago, twice a month, ..

Route de strasbourg is a free  three-lane road, go through luxembourg, stretch more than 150km, the trip, needless to pay less gasoline if the advantage evaporates on the asphalt - I do not know where you go in uk - but if you pass by luxembourg, then it is better to go to take the sea ferries from Zeebrugge to Hull.

https://www.google.it/maps/dir/Zeebrugge,+Bruges,+Belgio/Lussemburgo/Colmar,+68000,+Francia/Basilea,+Svizzera/Como,+22100+CO/Bologna,+Citt%C3%A0+Metropolitana+di+Bologna/Ancona,+Provincia+di+Ancona/@46.8018371,4.4811258,6z/data=!4m44!4m43!1m5!1m1!1s0x47c4a9960457b1c7:0xd81836ede612e886!2m2!1d3.2068507!2d51.3189468!1m5!1m1!1s0x479548cd9df32c57:0x400d1d6d1056d10!2m2!1d6.1319346!2d49.611621!1m5!1m1!1s0x479165dff670c1cf:0xe35d7e3e616ce966!2m2!1d7.358512!2d48.0793589!1m5!1m1!1s0x479049c72769304f:0x361ceb70f36d8a90!2m2!1d7.5885761!2d47.5595986!1m5!1m1!1s0x47869c481027ed63:0xb99b96af785ff524!2m2!1d9.0851765!2d45.8080597!1m5!1m1!1s0x477fd498e951c40b:0xa2e17c015ba49441!2m2!1d11.3426162!2d44.494887!1m5!1m1!1s0x132d802a2447a9c3:0xfad5680543fc5ac!2m2!1d13.518915!2d43.6158299!3e0

if you leave in the morning around 10 am from Ancona, or maybe before, you can stop to sleep in Colmar - you just have to make sure to get to Basel, at least around 16/17 pm - because in that area, for about 50/60 km on route de Strasbourg, (also called the streets of the Ardennes) with the setting of the sun, fog arrives - I used to do this route, about twice a month, a few years ago - departing from Todi ( Umbria )

for my driving standards at the time 800 km in 7 hours, they were not a problem - but I was traveling alone and with fast cars - if the ferry arrives in Ancona at 2 pm. hardly, you will arrive at the Ancona motorway toll booth before 3pm. (considering that the 22 is saturday, and transiting against the current from the sea to Milan, the highway should be quite smooth), if you do not find interruptions, and you limit yourself to a coffee / fuel stop, you should be able to get to the west junction of Milan, in direction Como at 7pm. and my advice is to sleep here - there's a Holiday inn, at the exit of Assago (about 80 eur double bed). https://www.ihg.com/holidayinn/hotels/us/en/milan/milas/hoteldetail?cm_mmc=GoogleMaps-_-HI-_-IT-_-MILAS

I agree with Ugo about how far you can get on day one - Como seems about right - about four and a half hours driving [plus stops] - 280ish milesHowever, that does leave about 660 miles [11 hours + stops] to go via Luxembourg, or 625 miles [10 hours 15 minutes] via Ugo's route.  NOTE, although its more direct, Via micheling calcualtes its about £16 more expensive because of tolls, and you don't get the cheap petrol]8 hours or so driving the next day would get you to Namur area - Booking.com site has some cheap hotels for that area, and it would leave about 3 hours the next day to get to Calais.  Midday ferry or Shuttle should let you get to Peterborough that evening.Remember you have to pay on line, or by phone, for using the Dartford Bridge these days - there are no toll booths to pay when you get there. Good luck

I suggest near Milan , because Como ( on this holidays time ) , is more expensive . and Yes , Alan , but if  they  embark to Zeebrugge and land in Hull, which I really used to go to Manchester ! avoid losing a lot of time on the route to calais and above all, go around London - Regarding  travel 625 miles in 10 hours ( average 62km / hour) - well ... but you British, still circulate with the Alvis?  in 1992, I went to Moscow, with a jeep cherokee diesel , in 2 and a half days ..  

Looking at getting to Peterborough about midday on 24th.If you haven't already booked the ferry from Calais, look at the overnight sailing from Hook of Holland to Harwich. Leaves Hook at 2200hrs and lands at Harwich at 06.30hrs and is only about 2hrs to 2hrs 30mins to Peterborough.Costs about  for a car plus 2 adults is about £250 return  [but saves cost of a hotel stay on route] Could be worth looking at.

less expensive from Zeebruggehttps://www.ferrysavers.co.uk/Search?sid=1c87b58f9618d49efa69c46557e58d570

Right !This is the link to the search page, select you, according to your needshttps://www.ferrysavers.co.uk/