Well, there are lots of sites available to help you find long lost commrades and friends. For example, the very popular Friends Reunited site has a dedicated section to army friends. Here's what they've got to say about their service for the services:
Finding Army friends just got easier thanks to Friends Reunited.We’ve got thousands of old Army friends listed on the site in our Forces Friends Reunited section. If you’re looking for Army friends that you served with during your national service or during the war, you can look them up on Forces Friends Reunited.
Army friends from Army bases around the world can also be found.
