I agree, learning English should be a condition of gaining benefits here. It's difficult to tell whether the ones who won't learn are genuine immigrants who want to work or "scroungers". Unfortunately, there are cases where the UK has made it easy by providing interpreters for everything from claiming benefits to driving lessons. Brits can be lazy when learning languages as they're not taught early enough in school; English is taught from age four in some countries.
Experience on holidays has mostly been locals very eager to practice their English skills. Greeks are very pleased when a non-Greek attempts a few words of their language, especially as it's difficult to learn. I think the number of English people abroad who try to make themselves understood by shouting is diminishing, with many keen to integrate into the community. Indeed, some communities in Spain provide free language lessons to welcome new residents.