UK & Europ Prepaid MicroSim


I am taking my iPhone whilst I am traveling to keep up with whats happening around me.

Is there a certain phone provider that you can get a prepaid MicroSim from in UK or Europe to use in iPhone.
I am on Optus contract but am unlocking my phone before I go.

I have heard a few people say that getting an “Orange” prepaid account in UK is the best and will work throughout EUR. is this true and if so can someone please confirm. if not can someone also recommend a provider that allows phone/txt/data at good rates?

Let me know