I thought automated workflows was a big part of mailchimp
It is, but for emails the customer explicitly opts into. These sort of transactional emails are not covered under that. No professional developer would help you with this as there is a risk that your account will be flagged for sending spam. You'll need to look at using a different service (or an app as Gopi suggest above).
I could be wrong of course - wouldn't be the first time!
Take a read through the acceptable use policy:
http://mailchimp.com/legal/acceptable_use/
Specifically this line on Prohibited Actions:
- Send transactional messages through MailChimp, unless you use our Simple Transactional Service or Mandrill.
Also of interest:
http://blog.mailchimp.com/what-is-transactional-email/