[Sangetsu]

Though you are married to a Japanese, getting a spouse visa won't be automatic unless your wife makes enough money in Japan to support you, or her parents agree to sponsor you.

Considering your experience (or lack thereof), teaching is probably your best option. You probabaly have enough university credits to get into a school where you can get a CELTA certification. With no degree you will have to take the course in Thailand or the Philippines (where admission standards are more relaxed), but the certificate will still be accepted, and is really the only one worth having.

On the other hand, most schools in Japan don't know one TEFL certificate from another. You can make your own on your computer and print it out yourself, the'll never bother to check. But with a genuine CELTA, you can get into a better situation in Japan, and you can also use it to get a teaching job if you return to the UK, or wish to teach in another English-speaking country.

Getting a CELTA costs a couple thousand dollars or so in Asia, and takes about 6 weeks. In the UK or America it'll cost more and take longer.

As for other jobs in Japan, I wouldn't bother. The median income in Japan is lower than America or the UK, but the typical teacher's salary in Japan will put you at the median level. Pay starts at around 3 million yen per year, which is more than double what restaurant workers or store clerks make. You won't get rich teaching English, but you'll be able to support your family doing it.