I'm in London rightnow and I do want to visite it, but I don't know what is the easiest was to get there and the price because there on some Web site it's free and others you have to pay. Can you give me those informations.
I know your trip is probably long over, but the question is worth answering. Kew Gardens have an admission charge - full details at www.kew.org/Kew-gardens/plan-your-visit-to-kew-gardens . I had to check myself what the current charges were, because I'm a Friend of Kew so have unlimited admission. Anyone wanting to visit regularly should consider becoming a Friend; the break-even point is seven visits a year for an individual friend visiting alone, but an individual friend can sign in another family member for free, which makes the break-even point four visits a year if you both visit together. There is no admission charge for Kew Palace, but you have to pay for admission to Kew Gardens in order to visit Kew Palace (it is not possible to avoid the admission charge for Kew Gardens if you only want to visit Kew Palace). The easiest ways to get there are the District Line to Kew Gardens station (on the Richmond branch) or rail to Kew Bridge Station (trains depart from Waterloo station). It is also possible to get there by bus; the 65 stops nearby, but that route runs from Chessington to Ealing and goes nowhere near the centre of London. I strongly recommend the Citymapper app, which is, in my opinion, the best way to use public transport in London.
There is just a lot to see and indeed one wouldn't have enough time to visit all the attractions in a day. Luckily, I bought an annual membership pass, which enabled me to visit this place very often. Do check the membership benefits.