To be an ESOL teacher you will need a teaching qualification and a subject specialist qualification.
You may be able to study for a Diploma in Teaching English (ESOL) in the Lifelong Learning Sector. This is often offered as a 2 year part-time course at a Further Education College.
Alternatively you could study for a generic Diploma in Teaching in the Lifelong Learning Sector (DTLLS) and an additional diploma unit (tba). This may take 3 years part-time.
For more information on other routes, please check www.lifelonglearning.org.uk