I wouldn't particularly hold your breath for Vodafone bringing in Visual Voicemail service in the next five/six months as there's people out there who've been requesting it for quite some time now.
It's one of those things, a nice to have but not really a need to have therefore some networks don't see it as essential.
But to answer your other point, all networks will be offering free roaming in the European Union on June 15th 2017. I say free, it just means you'll be charged the same as if you were here in the UK so you'd be able to use your allowances etc.
Even with the UK commiting to leave the EU, it will be a minimum of two years till this process is complete so only then will we understand if UK operators are going to withdraw from this regulaton.
This is why 3 have updated their 'feel at home' offering to include the EU countries it didn't include previously.
I do have to say though, Vodafone's offerings over the past year with inclusive roaming have been great and have done what they said on the tin. There's been no slowing down of the data (unlike 3 feel at home)
If you're interested in what's coming this summer though, check out: https://ec.europa.eu/digital-single-market/en/roaming-tariffs
