From the 26 April i am in London England for 10 days . I know my streak will end but my crowns ?
Your streak doesn't have to end if you have the app on a tablet or smart phone, or can access the website version somehow. London, of all places, shouldn't be in the internet wilderness. That said, streaks are just pixels and useless lingots, so it's not something to worry about too much.
If you have a phone with a Wifi connection:
There are so many good pubs and restaurants in big supermarkets in GB with rather good Wifi.
Set your daily goal to a maximum of 10 XP, have a nice drink and 1 lesson in Duolingo.
Or, don't think about Duolingo. You will lose your streak but you will keep your crowns!
Have a great time in my favourite holiday destination!