That's great if you are visiting for a few weeks or even a couple of months, but do bear in mind that the free EU roaming does require that you spend most of your time in the home country, i.e. if you live in Germany and use a UK contract for a year you should expect to be charged extra.
Of couse the UK government are probably going to lose you the free roaming right anyway as part of their ideology-driven approach to brexit. So enjoy it while you can...