Ott: You people spell fiber and yogurt funny.
You mean correctly?
Am I allowed to say that I may or may not want to kill the prime minister?
Yes, but it won't make you popular. Killing legally-elected political leaders is generally frowned upon.
Also, bear in mind that Britain doesn't legally have Freedom of Speech.
You're not like to be arrested for being insulting (
although that is a thing, stupidly), but you don't have the right to say what you want. Threatening, Racism, loveism, Homophobism and other such things can get you arrested. Excessive swearing is also means for arrest as a "breach of the peace".
You won't be arrested for swearing, really, but if you're making a big scene and just shouting constant swear words, you may be.
Where are you staying, currently?