I hope the title explains it all. I supply goods which are taxable in UK. If the EU customer is not taxable, should I zero rate it or is the transaction outside the scope of VAT ?
If your customer is VAT-registered in their home country, provides their full VAT number, and you do some paperwork, then it's zero-rated for VAT. If your customer is not VAT-registered, then you need to charge VAT the same as if they were in the UK. See here for full details.
However, if you're selling more than a threshold amount to another EU country (generally a few tens of thousands of Euro, but it varies by country), then you have to register for VAT in that country.