Best sim only for unlimited data, UK and Europe roaming?

[tsobo]

What's the best sim that comes with unlimited UK and Europe data roaming?. Due to change of contracts, I might be travelling a lot more to Europe, so considering an u limited data sim?. Most networks seem to have fair usage policy of around 40gb to roam in Europe, but need more. Many thanks.

 

[tsobo]

Smarty has worked quite well for me in Europe but if I was travelling more frequently then I'd pick up another SIM from another MVNO just for "redundancy" in case the backhaul to the UK is congested with SIM 1 for example.

What's their fair usage though for Europe?