There are definitely advantages to taking your cert course in another country as you in a prime position to assess the local job market whilst you complete your studies. Your trainers will also be able to offer advice about how best to find employment locally and what conditions you can expect.
In addition to this, the teaching practice component of your course will prepare you to teach local students and help you understand what difficulties this may involve, although some might argue that taking the course in the UK will give you teaching experience of a wider range of student nationalities which can help later in your teaching career.
Spending time in the country, with accommodation and support network provided by the school, can also be preferable to turning up ‘cold’ and having to find a job and somewhere to live with no help or contacts.
TEFL International offer a twin centre option where you spend the first 2 weeks of the course in the UK and then the last 2 in one of their other centres worldwide. I know they run this option with their centre in Costa Rica.
You can find details at: