This question really can't be answered, because you did not state where you're flying from. It costs a lot more to fly to Los Angeles, (Hollywood) from New York, New York, than it does to fly from...
Flies can range from $.50 to $10. Some flies are made my special artisans and can become almost like collector's items, therefore their price will be much higher.
That depends on many factors, such as where you are flying from and which Airport in England you want to fly to (there are many), what class of travel i.e. Economy, Business or First Class. When you...