Itinerary question

It would help if we knew how you were planning to travel between Bruges, Normandy, and Paris. We did much the same trip some years ago, and we started in Paris, then rented a car and drove to Bruges, then went to Normandy (and went south from there on an extended trip through France. Since the trip lasted more than 3 weeks, we found it handy to lease a car. Peter

I'd say London first. Train to Bruges. (Via Lille or Brussels on Eurostar?) After Bruges, train to Lille; pick up a rental car and drive throughout Normandy, which is very easy to do; and drop your rental car off somewhere in Normandy such as Caen, Rouen, etc. Or Rennes if you make Mont St Michel/Brittany a final place to visit in the region, and take the train into Paris.

Dropping and returning a car in different locations in France isn't expensive, but if you were to rent in Belgium then drop off in France, it's quite expensive.

Or fly into Brussels to visit Bruges, and after Paris take Eurostar to London.

It would help if we knew where you were flying from, but generally you will get better deals and sometimes non-stop flights to London, which you would probably never get if you were flying to Brussels. So I would start checking flights and see what you come up with, then decide. Do you plan on taking an open-jaw flight and doing your return flight from Paris?

I like KD's plan. Keep the car in France (or return it in France if you drive into Belgium) to avoid the big dropoff fee. Open-jaw flights using Paris and London, or vice versa, will save you time and money. You might find a good fare using Amsterdam, which has good train service to/from Bruges.

What sequence to use, I think, depends on what fares and schedules you find. Here's a useful tool for exploring options, but you should double-check with the actual carriers and buy your tickets from them. And here's a good way to explore car rental options, and also to do the actual rental. Have fun putting this together.