Applying for a visa whilst Travelling in Asia?

I am a uk citizen living in New Zealand. i leave here in 3 weeks so getting a L type in nz isnt an option from what i have seen from the requirements on your website. I dont have a specific date of travel right now either (I just know the month will be april) However by 18th march i will know the specific dates. How do I apply for a Tourist type whilst travelling?