The online webtool at https://ee.co.uk/help/mobile/roaming/roaming-costs allows you to check your specific plan for whether any add-ons are included, the same should be possible by texting RO followed by the name(s) of the countries you are visiting.
The default position in the EU is a £2.59/day charge for the use of your UK allowances, subject to a 50GB/month FUP on data. This can be reduced to £15/week or £21.50 for 12days.
If you have an Essential Plus, All Rounder or Full Works plan, the chargeable add-ons are inclusive. Whatever your billing options, ensure you enable the free roaming facility by texting ROAMING to 150 before leaving the UK. This unlocks access to foreign networks and thus ensures you have coverage abroad.
