Hey there,
I checked American for you. It doesnt seem they fly direct to Detroit' you'd have to change in Chicago or New York.
British Airways does fly direct to Detroit from Heathrow; I was playing around the dates and if you leave 14-Oct (Tues) and return 02-Nov (Thurs) it would be 415 pounds total for one adult.
Virgin Air does not fly direct to Detroit; you'd have to stop in NY and take another airlines.
United doesn't seem to fly direct; you'd have to stop in DC (Delles.)
Continental is crazy... From London, to Jfk, the cab it to Laguardia, then fly to cleavland and then detroit. Geez!
I know you probably want to spend as much time with your family as possible (and dont want to change flights) but Iceland Air is really cool. They allow a 3 day stopover free in Iceland!! You'd have to change planes at JFK though...
If you (or your husband) takes any Uni classes, you can get super cheap flights thru
http://www.statravel.com (Student Travel.)
You can check out the travel websites: Expedia, Travelocity, Orbitz and Cheap Flights- not sure if they accomodate UK citizens but they might have UK websites thru the American versions. Sometimes though they offer the same prices as the airlines websites so check both before you book. Occasioanlly you can get a discount booking a flight directly thru the airline website. Also, phone them and ask if there are any special discounts. Remember, its always cheaper to fly Tues through Thursday~ occasionally Monday also has the same prices as Tues-Thurs. (You probably know all this already!)
If you do end up having to switch in NY, you would have to use a "large" airlines as Southwest only leaves from Long Island (about 40 min east of JFK) and JetBlue does not fly to Detroit.
Did you fly direct to England when you came over? Which airlines, if you did so? I can further research that airlines then.
Sorry I couldnt be of much help.
