Having lived in England for 5 years of my adult life, it was a pleasure to read your post, Heather. Your advice is spot on!
I remember feeding the pigeons at Trafalgar Square. English pigeons are nothing like American pigeons! They are friendly, like to get up close and personal and will coo in your ear for a seed or two. It was fantastic!
The seaside amusement parks in England are great fun for both adults and children.
I did a lot of exploring London on foot and really enjoyed myself. The double-decker tour busses were fun too. I wandered into the British Museum one day and was so disappointed that I didn't have more time. Treasures from all over the world are stored and displayed there. It is truly like traveling back in time.
As a big fan of Marion Zimmer Bradley's "The Mists of Avalon", Glastonbury Tor was a magical place for me. I had expected Stonehenge to be bigger but it was still a marvelous monument to see.
I would offer a couple of suggestions to people traveling to England for the first time:
1.) Plan on sleeping on the flight over. If you fly out in the evening and arrive in England in the morning after having slept during the flight, you'll have a jump on jetlag. Have the kids pack pajamas & Teddys so they can sleep comfortably on the flight.
2.) Don't spend all your time eating at McDonald's! Go to a real pub, eat pub food and (if you're a drinker) get yourself a pint of Scrumpy Jack!
3.) Fly Virgin Atlantic. Richard Branson is a millionaire because he knows how to treat his customers. Of the many trans-Atlantic flights I've taken, that is the airline that most impressed me with service and amenities.
Have a great trip, Heather! This will be an adventure your daughter will never forget!