Hi AsetAcc.
If you're providing training services to companies outside the EU then the supply will be Outside The Scope of UK VAT.
You don't need to state this on the invloice.
If you are invoicing companies in the EC then the VAT will be accountable by the company in their country under the reverse charge procedure.
You can state 'reverse charge supply' on these supplies to EU businesses but there is no legal requirement to do so.
Please see guidance below:
6. The place of supply rules for services
9. Services supplied ‘where performed’
Thank you.