Doesn't look good just yet..... (https://www.vodafone.co.uk/explore/network/network-improvements/wi-fi-calling/)
A compatible device:
Samsung – Galaxy A3 (2016 and 2017), A5 (2016 and 2017), S6, S6 edge, S7, S7 edge, S8, S8+, Note8 and XCover 4
iPhone – iPhone X, iPhone 8, iPhone 8 Plus...