We cannot say how long it will take to get there nor how long a visit will last as these are very subjective questions.
It will take longer to travel to the museum at weekends and during school holidays. During school holidays there is normally a significant queue, especially first thing in the morning. This queue can be anything up to 2 hours long, sometimes longer. The Natural History museum around the corner has even longer queues.
The Science museum is an extremely large museum featuring a great many different displays. The length of your visit will depend upon how long you linger over such things as: Watson and Crick's actual DNA model, Stephenson's Rocket and the Flying Bedstead.
As a guide it took a family with 3 children under 7 (with associated short attention spans) a day to see approximately 1/4 of the museum in passing. An indepth visit with older children or just adults would take significantly longer.
The Natural History museum is considerably larger and more complex and a visit there will take much longer.
About two hours but much depends on which part of London you are driving from.
The iconic red London Routemaster is 11.23 metres long.
The Eurostar travels between London and Paris, and between London and Brussels. It does not travel between London and Geneva.
London-New York takes 7 hours. London-Boston takes slightly less, but there isn't much difference.
3 hrs
Three to three and half hours, it will be much longer if you stop in Paris or London.
Because there is so much information under the heading 'science' and this amount keeps growing, it just takes too long to learn everything there is to know
The Tower of London isn't for sale.
10 hours
if have too much of money you can study in London
London Bridge in London is free to cross.
How much time takes India from London by air