My pension letters.

Hi I'm considering travelling across Central America for over a year. I have done this in the past. many years ago. Now I'm retired and have plenty of time on my hands. I'm looking for information regarding my mail that is sent to me by the pension department here in England. I can hire a post box here in England but it costs a lot of money just for two letters, I have been in touch with the international pension department. But they were not much use. I will not have a permanent address in Central America. I would notify the pension department. But if they can't contact me by post, they will think I have passed away.

Would be grateful for any help i this matter.