Quickly browsing your site I noticed a few things:
The photograph (on the home page) of a tea plantation with the sky and tea mountains in the background comes across blurry/pixelated on my screen. This does not seem professional. I wonder what it would look on the front page to mix up having green leaves (tea leaves/tea plants) with a bowl of freshly brewed green tea, this way it's staying with your green theme while adding more variety to the types of photos on your homepage. Also, that's what essentially people are going to be doing with your product, drinking tea.
Scrolling to the bottom of the homepage, I noticed a green block of color. The color is abrupt, when compared to the lush looking photographs. Instead of this block of color, what would it look like to have a softly-lit photograph of the tea one would actually be getting in your subscription (maybe with the vessel or box that it comes in the background) (I could see a smaller block of green included)? This way someone who is scrolling through site can visually make the connection, "ah yes, this is what I am getting" without having to navigate further into your site.
Reading text box "We'll send you the finest loose leaf tea from stunning Indian backwaters, Chinese mountains, tiny islands off Portugal and the alike" I wonder what what it would look like to hyperlink the words "Chinese mountains" "islands off Portugal" and/or "Indian backwaters" so that people visiting your site can, in one click, go to your Chinese mountain tea or Portuguese grown tea. Right now, I have to navigate further into your site to find that info, unless I want to learn more about your Matcha challenge linked in the first text box.
Additionally, the white box surrounding the text "All from 48p a day!
Including postage" seems too large when compared the other white text boxes on your homepage, no other white boxes on your homepage have that much empty space. Again this doesn't come across as professional.
I like your logo, and the menu bar at the bottom and top of the homepage is well laid out and attractive.