TEFL and ESOL are fairly much the same thing. Teaching English as a Foreign Language (TEFL) and English to Speakers of Other Languages (ESOL). There are a range of courses which will qualify you to do this, bear in mind that it is very competitive and there are few placements teaching English to rich foreigners, one-on-one. The reality means long hours and poor pay teaching students who are usually only there for visa reasons, in a cr@ppy room on Oxford Street! Having said that, if you are going travelling, it could be quite useful, depending on where you are going. If you are serious about it, you should pay a bit more and do a proper course, rather than a cheaper, weekend 'intensive' alternative. Cambridge or Trinity are the two main ones. Cambridge sounds better to foreign people, who don't know better, otherwise there is little in it.
As for literacy tuition, it depends on the age group you want to work with. Register with a private company to do GCSE/ A-Level support. The money is ok. Or advertise locally, ie corner shop, to avoid paying a fee. Bear in mind people wanting to hold you responsible if they don't get their grade....!
Good luck.