No offense, but if you don't know the exchange rate or can't find it on your own at 45 years of age, how are you going to survive here? Look up currency converters on the Internet, or just use your local newspaper, financial page, for the daily exchange rate.
3500 yen is approximately 15 British pounds today.
BTW, there is no "standard price" for private lessons. Some greenhorns ask a mere 1000-1500 yen/hour, while other people get 3000-5000 yen/hour per student, and other people get even more. You don't even have to charge per person per hour; sliding scales are also used here, or monthly rates. How much you get depends on where you are, who you target, and how you market yourself. Your wife is mistaken about getting 40 pounds (9000 yen) per hour from a single student. Not many get that these days, and the only ones I know of are very experienced. I don't know of any Japanese teachers asking for or getting that much for Japanese lessons, either.
Agencies don't always set the prices; they usually only set up the initial meetings between potential students and teachers. The rest is up to you.
You can
perhaps set up a "full schedule" quickly (depends on where you live, for one thing), but students are cheap and fickle, and many prefer teachers with experience. Younger students (teens and 20-somethings are very stingy, as are some older types). Many private lesson students will drop you without notice, too.
I met some english teachers out in Okayama who were really nice guys, but seemed to think I would have to leave my job to pursue this path.......I dont think i do
You haven't really described any path other than a desire to change careers and be here in 10 years. A BA degree in English lit is not going to get you anywhere in Japan, other than entry level teaching jobs. You really need to think things out long and hard. You want to come here for a change of careers? Prepare yourself for it with the right education, experience, and language ability. Teaching English is practically the only job here that doesn't require much (if any) Japanese ability. It'll get your foot in the door, but coming at 55 to teach is pretty lame, especially if you have 10 years to plan for it. Again, no offense intended, but what you have just described is pretty incredulous to me.
Look at
http://www.daijob.com (there's an English page linked) and see what is offered. Many are bilingual jobs, but the point is, you are going to need fairly high fluency to get by with other than teaching jobs. The only exception I can think of is if you get a job in the UK with a company that has a branch here which uses little Japanese and is willing to send you here.
....other people must face the same issue...its not unusual to have a full time job and study.....i am happy to pay for it...
is there a way around it?
You can have a FT job and go to school, yes, but I think it is pretty obvious that such a thing will require lots of your time, working 8 hours a day, traveling 1-3 hours a day at the main job, and studying a few hours a night. You'd better have a job that can support your family. Want kids? Think more salary than an entry level teaching job, too. That's only about 200,000 to 250,000 yen/month these days and going down (yup, pretty much in line with what you have already discovered). Throw that figure at your wife, along with any distance learning tuition numbers. I hope she is willing to work and hold off having kids for a while.