Hi Matthew,

I think the fact that you have a degree and some teaching experience would be enough to get you a place on most Master's courses. Having said that, I think it would be useful for you to do some reading up on methodology and language issues beforehand to build up your background knowledge considering that you've come from a science background. I think that Jeremy Harmer's site www.eltforum.com might be a useful resource for you here .. it costs about $35 a year to subscribe. The books in the "how to .. " series edited by Jeremy would also be useful .. eg How to teach Grammar and How to teach Vocabulary by Scott Thornbury.

There are many hundreds of MA courses available around the world. You'll need to decide where you want to do it - whether you want online or face to face etc - and also what blend of classroom / theory focus you want. Also, what you can glean about the concerns / research specialisations etc of the particular university would be useful .. for instance, here in NZ, Victoria Uni in Wellington has a strong focus on vocab learning because of the prof there (Paul Nation), while at Auckland Uni, there's a stronger focus on task-based learning (Rod Ellis is there), while at AUT also in Auckland, there's a strong focus on writing / correction etc (John Bitchener's special research topic). Where I'm studying (online from Macquarie in Australia), there's a big faculty, but one of the big topics is text and discourse and in particular Systemic Functional Grammar (following Halliday, Matthiessen, Martin, Butt etc) and language testing (Geoff Brindley).

Anyway, if you don't have any idea about what areas would interest you etc, don't worry about it .. there are other criteria about price, location, reputation, convenience etc to think about too.
good luck