The key to getting a job is to get the relevant qualification. In the UK and most of Europe the most recognised qualifications are the RSA or Trinity House Certificates in Teaching English as a Second Language. These courses are normally of four weeks' duration and are very intensive; involving 8 hours attendance per day, plus 3 hours homework each evening. Having done the course, I would highly recommend it.
Once you have the qualification, it is quite easy to find work. In the UK, overseas jobs are advetised in the weekly Times Educational Supplement. There are also agencies which can help you. If you wish to remain in the UK, there are opportunities in colleges, adult education institutions, prisons, the voluntary sector and with private training providers.
Please bear in mind that any organisation which offers to take you on without the relevant qualification is unlikely to be reputable and unlikely to offer a decent salary.