My advice to you would be to stay in England mate.

I cannot remember the exact exchange rate, but you should be looking at between 3,800 - 4,500 RMB (around maybe 350 - 420 pounds) for 16 classes a week. You should also get a one way cost of your airticket reimbursed for a 6 month contract, plus other benefits. Your electricity/gas/water and telephone should be free although toll calls are at your expense. If you have a good Uni/school/college they will also supply you with a PC with internet access for free.
What city is the job in ?