Well if you've never really travelled before, Hong Kong is going to be quite an unforgettable JOURNEY
I found I enjoyed Hong Kong much more than almost anywhere in mainland China, but that may have more to do with my own tastes etc.
English is pretty common, and you shouldn't have TOO much trouble getting around... the transit system is really great (air-conditioned subways!) and is really convenient. Even the bus system is pretty well maintained and efficient. I found restaurants often are Cantonese-speaking only, but it's pretty easy to point at picture menus, or you could ask for an English speaking waiter sometimes.
I'm not sure if you need a Chinese visa or not... I got one when I went, but I was going to the mainland during the same time and can't remember the specifics anymore. It's something to look into for sure, as you would need to arrange well ahead of your trip.
There's tons of stuff to do in and around Hong Kong. make sure to save at least a few full days for sight seeing outside of the tea expo. Bring comfortable walking shoes
I recommend getting around to the other side of the island a bit... Stanley, and Repulse Bay area are a nice change from the hectic north side of Hong Kong island and only about 30 minutes via bus.
See Victoria Peak (of course). I'd also highly recommend taking a day-trip out to Lantau island to see the giant buddha, and ride the friggin' awesome glass bottomed cable car! Perhaps stopping at Tai O village to see a rural side of Hong Kong that is almost completely gone. You could also take a day-trip to Macau via hydroplane (if you like gambling)
Also... DIM SUM! There's lots of options, and everyone has their own favorite. As bizarre as it sounds I really enjoyed the traditional cart-driven Dim Sum they serve at Hong Kong City Hall... I went back multiple times.
Just get their right when it opens at 10:30 (or 11?) or you'll need to wait in line.
I didn't do a whole lot of tea-related stuff when I was there. There's an OK tea museum in Hong Kong park, and a great little teahouse next door where you could drink the afternoon away.
You're not likely to run out of things to do in Hong Kong.