Three UK or Vodafone UK for SIM card in Greece?

I will be in London and then flying to Mykonos and also visiting Santorini and Athens. There is a Three UK SIM available that gives 12 GB data and 3,000 minutes and is very reasonable and supposedly covers Greece.

Cosmote have the widest coverage in Greece with Vodafone and Wind being other providers. If you get a SIM in the UK to cover all your trip, it should give free roaming in Greece. All you need to do in Greece is to connect to whichever network gives you the best signal.

www.three.co.uk
Greece.
Including Crete, Corfu and the other Greek Islands.
地図上では4Gエリアとなっていますが、UK3は本国以外は3Gの筈。

January 12th, 2020
Three offers inclusive international roaming in 71 destinations including most of Europe, the USA, Australia, Brazil, Singapore and more.

ThreeThree offers a mobile roaming package known as Go Roam for its UK-based customers (previously known as Feel At Home). For customers on an eligible plan, the charges for using your mobile phone abroad in 71 destinations have been removed. This means you’re able to use your normal UK allowances including your minutes, texts and mobile data at no extra charge.

時代遅れだと思っていたが、ついにローミングでのLTEも始めたようです。