I'm sorry to say, but the simple fact of the matter is that PGP/GPG isn't used anywhere in corporate life. Not even in banking-related companies.
For one, people don't perceive email as something that can easily be snooped, and if they do they'll think it's something like a chance encounter as if it's a regular piece of mail where you have to be at a certain point at a certain time to be able to snatch the mail, plus have to have a reasonable idea what you're looking for as a mail thief.
Secondly, and I cannot stress this enough, it's a f'ing drag to use. It's not easy to install. It's not easy to set up, and it's far from user friendly on a day to day basis.
Besides the fact that email encryption isn't commonplace, as long as you aren't sending you pin number or medical data on a regular basis (daily), why bother to be honest. You'll get a stamp as "that weird guy" if you start about PGP etc, and that'll last. If you want to send it securely, just wrap it in an encrypted container, like a ZIP or RAR file and phone them the password.