The demand for English language teaching in the UK can be divided into two categories, permanent and summer school. Permanent positions are hard to come by as every year many very experienced and qualified EFL teachers return to the UK in search of employment. This creates fierce competition for available jobs. This is perhaps surprising considering that these jobs are not usually on competitive salaries when compared to the cost of living in the UK.
Summer school work is a different story. It is estimated that there are over 800 language schools in operation during July and August catering to foreign students on intensive English language learning 'holidays'. This creates a huge number of opportunities for a qualified EFL teacher. Such positions are often well-paid and sometimes (in the case of residential schools) even come with free accommodation and meals.