Does a Nintendo Wii bought in Japan work in England?

You could use a stepdown transformer so that it'd boot up, but I'm not sure about firmware updates or game downloads, as these are based on region, (even though you can set a consoles area of residence, I'm not sure if this will resolve this).

As for games in the UK, you can get these to work on your Japanese machine I believe by buying the Action Replay Freeloader by Datel, (this makes UK consoles region-free without modifcation, though I'm not sure if it'll work on a Japanese machine).

You could always buy a UK console, and sell the Japanese one on eBay, and hope you get a bit back for it.

As Scott Bull said, you need to change the flow of power leading to your console. If you hooked it up to a UK power supply your Wii would be fried. Get a step-down converter (most electrical stores will have them) and make sure your UK TV (whose signal is known as PAL) can show images from an NTSC machine (Japanese TVs use this signal). If you have a fairly modern television set you should be okay. After that, you'll have to get some software that allows you to play imported games (freeloader is the standard- you get buy it on the likes of play.com, I think) but these aren't always 100% reliable. If you don't sure software like freeloader then you'll have to use only Japanese games, which will be costly for you to import to the UK.

All-in-all, it's probably a lot more hassle to take a Japanese wii to the UK than it is to just sell your Wii and games in Japan, then buy a new one when you're in the UK.

I'm not sure about Japan, but I'm in SE Asia, and games here will not work on a UK console, and vice-versa without a chip added. The shops here will chip a Wii in order for it to play all the games (including bootlegs) but this invalidates the manufacturers guarantee.

No because the wii has a region block on it

You'll have to buy a UK power supply and if your TV is modern then it should work.

I really don't know because Japan isn't PAL