I would look for a prepaid sim which fits your usage in the country you arrive. As the European Commission is abolishing roaming costs within the EU starting with the 15 July 2017 the use in those Countries won't be a problem. Link

For Example 3UK offers a 30-day Prepaid Sim with 12GB Data, 300 Minutes, 3000 Texts for GBP 20 (25 USD). 3UK Pay as you Go Website
Activated with Feel like home where you can already use the Sim Card in 42 destinations including the ones you mentioned! 3UK Feel at Home Website