I know what you're talking about, I'm Vat registered and do business across the EU.
You're correct though, I misunderstood your question, it seems you're not even at that stage yet. You should really talk to an accountant, not HN. They will tell you exactly what you need to be doing.
Doing Vattable business with other EU countries is a pain. You will need whether each customer is vat registered in their particular country and either charge Vat or not based upon that.
Are you doing business to business sales, or business to customer?