You haven't posted details as to your Internet provider, email provider (your Internet provider or somebody else?) whether you are using POP or IMAP, whether you are using a secure server connection or not etc. Without those details it's hard to say.
Give us something to work with.
Your best bet, though, is your IT department at work. And if you're not supposed to be accessing your personal email from work or connecting your personal equipment - then don't. Most companies, though, are permissive about personal email. Just use a web interface (most ISPs and email providers have this for when you are on the road, in an Internet cafe, etc.) and make sure you use SSL if you are concerned about company snooping. (But realize, though, that a paranoid company might use keyboard loggers that could work around this.)
I worked at Sony recently for a couple of years, and they have a very strict policy: no personal equipment attached to the network, and no company intellectual property on personal equipment. There is guest access via WiFi in some conference rooms but it it for just that - guests. (It's on an isolated Internet connection with no connection to the internal network.) Of course, they issue company-owned notebooks to people who need them. You should read your company's policy and heed.
My solution is to simply use my iPhone for any personal email that is so important that it has to be attended-to during work hours. Which is pretty-much none.
In your case, I'd suggest that you probably should have waited for the 3G iPad...