Get the first aid certificate. Minimum I think should be REC level 2, which will take a couple of weekends and cost about £100 and is valid for 3 years.
If you are looking to work outside of the EU the next best thing to sort is the work visa for the country you are headed to.
Remember, if you are able to legally work in a country and can be flexible on start dates, have the right driving licence and attitude you might be more employable than someone with just an SMBLA or similar. If you are also handy with the spanners and they have a hire fleet you can add that as another reason they may employ you before you get fully qualified. Some companies just needs an assistant guide or a dogsbody to help run the place, clean up after the guests, and do the airport transfers etc.
Once you get out there you'll quickly rack up the rides that you need to log for the SMBLA Exams/test rides and you'll make good contacts whilst working in the trade.
Good Luck, the hours can be long, the guests annoying, the locals odd but the cycling is always fantastic. It was how I spent my gap year and looking back I'd definitely do it again 
