Thank you so much for your advice. I called the ABA again and talked through the breastfeeding class, and will be going to one of those in a couple of weeks. As the lovely woman on the phone said, it covers all the stuff you need to know whether you're feeding one or two - like attachment, nipple care, expressing, etc. And many twin mums feed one at a time anyhow.
BDT - I'll let you know how it goes.
Jen