Your Spanish situation falls into an unusual category and where QB  handles most common scenario's the code to handle this is ESZ

The Goods are in fact not an EC sale as they remain in the Uk so the Goods purchase using Standard vat rate and sale at cost also using standard vat rate is correct. You do not need to report in EC sales list.

Your service is zero rated and vat code ESZ cover this reporting the sale in box 6 alone.