Cheap World Phone

[RangerLG]

My wife is going to England in the summer for vacation and instead of taking her smart phone, she wanted to buy a basic unlocked phone and use a prepaid SIM from a carrier over there. I know about world phones, but does anyone have a recommendation on which type to get? Will quad band be sufficient? She will just have it in case she needs to call me from there. No data or texting needed. Any SIM recommendations? Thanks in advance.