What would happen in say, 1917 when it was getting bad in Russia, if the Czar and his family fled to the UK. Would have any great effect on the Russian Civil War. I doubt it would affect the ending of WWI to much.
Probably not. The Tsar was discredited and no one in the White movement really wanted him back. He would probably end up like the other Romanovs: rich and living a comfortable life in exile, but with no political power or influence.