Participants are usually young graduates, although many older people and those who are already teaching other disciplines study teaching English as a foreign language (TEFL).
They are not all expert linguists: you don't need to speak other languages. The entry-level courses leading to certificates from Trinity College or Cambridge University teach trainees to conduct classes entirely in English.
However, according to Christopher Graham, managing director of London-based recruitment agency English Worldwide, not everybody who enrols on one of these entry-level courses will end up teaching English, let alone doing so abroad. "People who are a bit older and already in work might be put off by the low salaries and lack of job security," he says.
Taking a good course is important. Tim Langley, manager of recruitment agency Saxoncourt, advises: "People thinking of doing a course should make sure it lasts at least 100 hours, there are six hours' teaching and the course is externally assessed and validated by a major TEFL body."
There are no figures on how many people take courses other than at Trinity or Cambridge. Schools don't keep records of where trainees end up and no central body monitors the spread of English language teaching globally. There is not even an agreed name for the profession: English language teaching (ELT), teaching English as foreign language (TEFL), teaching English as a second language (TESL), teaching English to speakers of other languages (TESOL) are all used.
One thing, however, is certain: it is extremely difficult to find long-term work in the UK without substantial experience or luck. This is partly due to the British Council, a UK-based organisation which is better known abroad.
The council was founded in the Thirties to promote British interests overseas. Its director-general, Sir John Hanson says: "The council's role is to maximise Britain's participation globally. It is a two-way bridge across which you can move people, ideas, materials, objects, skills, know-how. We don't promote English: people don't choose to learn it because of us. What we can do is to see that once the decision to learn English is made, the teaching is helped, supported and made better."
The council promotes the British ELT industry as well as providing its own courses abroad. It also aims to encourage schools to employ more experienced teachers by running an accreditation scheme for language schools in the UK.
"It's not easy to teach English. Until you have done a certificate course and had a couple of years' experience, you are not really that competent," says the council's accreditation manager Sarah Crawcour. Many organisations in Britain and overseas do not consider teachers to be properly qualified until they have completed a diploma-level course and worked as English language teachers for at least two years. This has created a catch-22 situation, making it hard for new teachers to find work.
According to Saxoncourt's Mr Langley, teachers' prospects depend on when they become available for work. "If they finish a course between March and April, then they have got an excellent chance of getting some work in British summer schools, which always looks good on your CV."
Mr Langley says the most popular destinations are Eastern Europe and Russia, Far East countries such as Thailand, Malaysia and Indonesia and - to a lesser extent - Latin America. "In all these places, the market isn't so well-established, so salaries are lower. In places like Japan, Korea and Western Europe, the salaries are higher so schools ask for more experience. "
"As a general rule, you get high salaries in unattractive places and low salaries in attractive places," says English Worldwide's Mr Graham. "You can save a lot of money by working in Saudi Arabia or Libya. " Salaries in Eastern Europe tend to be low by western standards, but in local terms they are extremely high."
Mr Langley advises new teachers to try to set up a job before they
leave the country so their employer will arrange a visa. However, a lot of schools rely on people who are passing through. If teachers go abroad to job-hunt, there is no guarantee of success, visas often have to be picked up in London and people need to support themselves until their first pay packet.
One solution is to go to Eastern Europe. Malgosia Zamolska-Settles, programme officer for Poland and the Baltic States for the charity East European Partnership, says: "People need other languages to do business with the West. English is by far the most popular because it's the language of commerce. " With schools mushrooming in the region, which has a low cost of living, it is relatively easy for new teachers to get established.
Another option is to take a part-time TEFL course over a year rather than the four-week intensive, or enrol on a course overseas.
"Studying abroad makes looking for a job much easier," says Alistair Dickinson, director of teacher education at the British Language Centre in Madrid. "You are here so you can see if you want to stay and you can look for a job while you are doing the course. It works out slightly cheaper and we can help find accommodation as well."
* Further information from the British Council, 0161 957 7755; embassies, the ELT Guide (yearly) and the ELGazette (monthly). Jobs and courses are advertised in The TES, ELGazette and Tuesday's Guardian, or contact recruitment agencies, international schools and voluntary bodies