Well you don't have to be that direct, but simply BE PUBLIC about your association with Alpha.
If you just let it be known that you are linked with Alpha, you'd be surprised how easily conversations develop, and invitations happen.
So associate yourself ... here are some simple suggestions.
1. "Like" our Alpha page on Facebook (click on the like button on the Alpha page here). Or, if you're a google plus user, do the same with the g+1 button.
2. Write a posting on your Facebook page about how your church is running an Alpha course, and you're wondering what to do about it ... add the link to our Alpha page.
3. Add an Alpha comment to the end of your emails, such as "Interested in Alpha? See here: http://www.stbarnabas.org.za/alpha.html)"
4. Put an Alpha notice in the back window of your car.
5. Have a small pile of Alpha cards on your desk at work ... pick up some from the church.
6. Bring Alpha into conversations. Like "Hmmm, someone gave me an Alpha flyer ... its unusual, what do you think of it?"
7. If you're a on-line type of person, tweet it.
Bottom line: simply bring Alpha visibly into your daily life and see what God does.