It was trip advisor that put me onto the hotel I ultimately chose. The reports were pretty good - central, small rooms but 'normal' for Japan, clean and handy facilities in the hotel and nearby. I felt it was cheap, considering it's in Tokyo, but I'm willing to take a gamble - I was expecting to pay around £200 a night for somewhere sensible'ish, but this one came out at just over £100 a night (internet booking deal).

Thanks for the notes on the geography of the station - I imagine it's going to cause me significant issues trying to locate the correct exit from the station and negotiating Tokyo street traffic, but I guess that's part of the 'charm' of travel-tourism.