Fleurpepper, just for info, UK state pensioners can still get an S1 and thus reciprocal public healthcare once they have residence (no need to wait for citizenship) in countries that recognise S1s. Of those, Spain is the simplest, since you can take your S1 to the visa interview and be registered for public healthcare at the same time as you get your visa. You do, of course, have to have a Spanish address to get the S1, but there are ways to manage that.
For other countries, one needs zero excess travel insurance (which is hard to find and hideously expensive - one of our quotes was £8000 for four months!) to cover the period between arrival and residency; in theory, weeks to a few months, in practice, for many places, much longer. Portugal, for example, recommends a year, even though residency should theoretically take only 3 months, and I know not to believe a word Greece claims about timescales.
Even with public healthcare entitlement, there may be costs that are unfamiliar to those used only to the NHS, and in many (usually ‘cheaper’) countries, it’s still sensible to have additional private insurance, as this buys you faster access and, to be frank, staff in the private sector often have good English.
On the wider language issue, lots of countries, including in the EU, offer, via local councils, free language lessons to immigrants. Not just a good way to learn the language, but to meet other (new) people too.