Lived there for two 3 month stays. The history and the architecture and the pomp and circumstance is truly a delight. I will return again and again.
It has too major drawbacks. One is the food, it is hardly eatable. All the dairy and meats have a chemical taste. My vote is start a severe diet when you enter the country.
Two: Everything is piercingly expensive. Don't arrive hungry. Bring survival bars. Get in and get out. (If you break down and need to eat go to a fish and chips stand the fish doesnt have that polluted taste, and they are closer to resonable in cost.

I absolutely love Kew Gardens. The entire area is just beautiful and there is always something going on there, whether it's an exhibit (I've been several times, but my favorite was when Chihuly had all of his glass works on display, placed in interesting spots across the gardens) or an event, such as the Easter Egg hunt which is held every year. This is another place which offers discounts if you carry ID (student, senior citizens, ect.), so I recommend obtaining some form of international id (for example, if you're a student, try and get an ISIC card).

The Director of the Royal Botanic Gardens, Kew, is responsible for the world’s largest collection of living plants. The organisation employs more than 650 scientists and other staff. The living collections include more than 30,000 different kinds of plants, while the herbarium, which is the largest in the world, has over 7 million preserved plant specimens. The library contains more than 750,000 volumes, and the illustrations collection contains more than 175,000 prints and drawings of plants.

An absolutely fantastic place for anyone who is interested in flora and fauna. Kew Gardens has one of the most extensive tropical and exotic collection of plant species found anywhere in the world. Kew Green located just outside the gardens is a nice place for a picnic and occaisionally local cricket matches are played there. Just be extremely wary of the weather conditions......in other words keep your eye peeled for the sun!

great place to visit if your interested in plants or just want to walk around I recommend the canopy walk or the palm hous. keep an eye out for the lizzard running around on of the rooms