planning a trip to scotland, ireland, london and paris any suggestions?

nikki asked: My friends and I are planning to see my friend in Scotland and plan to spend most of the trip there, however we want to take the train from london to paris. Once we are back in Scotland we want to go to Ireland any suggestions on how to plan this?

How long does it take to get from London to Paris and is it worth it for just a day trip?

stevethesquirrell asked: i am taking a vacation with my family…we will be in London for quite awhile so would it be worth it to take a day trip to Paris? and if so how long does it take?