In a small country like the UK it is easy to take interesting day trips, most people start their visit to the country from London so we will start from there.
You can easily visit Cambridge or Stratford by taking the many trains available from London.But if you want to visit a few places in the same day you either need to rent a car or take a tour.
I have found that Groupon often has a good sale on Day trips sometimes as much as 50 percent off.
You often have to visit the UK web site since for example the American web site does not show the tour or the discount.
Some of the most popular destinations are available I have saved 50 percent on tours all over the UK but they are almost always off season.
Here are some Pics