Ahhh, Japan, an amazing place. I spent 2 weeks of my travels there. I spent a week in Tokyo and then a week travelling west of Tokyo, to Kyoto, Osaka, Hiroshima and Nara.
Are you spending both weeks in Tokyo and then just doing day trips using the rail pass? I found that a week in Tokyo was actually more than I needed, and was very glad i spent a week checking out some of the other areas of Japan using the 7 day rail pass. If you want more info on places like Nara, Kyoto, Hiroshima and Osaka then let me know.
I wouldn't worry too much about the language barrier. I used about 5-6 words of japanese, and it was never too much of a struggle. all you need is. Yes, no, thank you, hello and good-bye. I thought about learning some phrases and had some, but any answer they give in Japanese you're not really going to understand anyway. They speak much better english than you'll ever speak Japanese so you can get by pretty easy in Japan, they all know the basics of the language and it's very tourist friendly in the main destinations. Also pretty much everything is also written in English and Japanese so don't worry too much about reading the symbols.
The fish market is pretty awesome, think I got up at 5:30am to get there just in time, it's pretty cool to check out and look at all the crazy fish they sell and to witness the tuna auctions , but as mentioned previously it is a working market so keep out the way, it's VERY hectic.
Try the english tea that comes in cans from the million of vending machines there are. It's awesome for an instant hot can of english tea :d also if you fancy a beer, the vending machines sell these too.
How are you accessing your money? I presume you will want to take some money out via ATM at some point, be aware that the only ATM's you can withdraw money from using UK bank cards are at either the post office or 7 eleven's. Make sure you remember the red logo/symbol for the post office if you do need one. 7 elevens are also everywhere.
Also when you pick up your 7 day railpass (if you're flying into Narita) you will probably need to buy a NEX ticket (Narita - Express) to get into Tokyo city centre from the airport. It's well worth buying that together with the Suica tube pass at the same time as it gives you the underground suica card and 1000yen of credit on it. This costs only a fraction more than a normal NEX ticket so is well worth it and is only available to tourists I believe.
If you have any questions about anything feel free to ask.
Useful Japan resources are:
www.japan-guide.com and
www.tripadvisor.com
