I applied online. The process took 6 months. I interviewed at Met Office (Exeter, England) in Dec 2012
Interview
Online application followed by a face-to-face interview at HQ in Exeter. Now there is an assessment center as well, they will cover costs for one trip to exeter but not both. The assessment center involves a group discussion session and a brief test of physics and maths. The interview session involves giving a short presentation about weather impacts at an airfield and then a board of questioners.
Interview questions [1]
Question 1
Lots of technical questions about meteorology, I didn't have much technical knowledge but they were more interested in how you applied information they gave you to the next question.