Costa Rica to Tijuana Mexico Via London

Well it is just the norm for me these days, I have to pick up a work permit for a job but is via some country thousands of miles away. I am traveling to Tijuana Mexico, a beachside resort on the Pacific coast of Mexico and to allow me to work there, I have to pick up my work permit in London, yes this is totally insane, i live 2 hours flight from Mexico city, but i have to spend 4 days flying to London and getting this piece of paper. I know I could have flown to Tijuana and told the immigration i was on holiday and they wouldn't have batted an eyelid, but my company have this policy of doing the right thing, they don't pay bribes and they don't have guys working without the correct paperwork even if it costs 10's of thousands of dollars to get the necessary paperwork. i don't really mind as i get to visit my old office in Bracknell and see all the old guys, who will look lots older than last time, i of course look much younger and far more dashing than i ever did, i am also full of sh*t.
Mexico could be good and the weather seems warm and dry from the forecast as long as i am not mistaken for a drug dealer and kidnapped and executed then all will be good.