Considering the degree of "hate speech" a Tweet would have to contain to land someone in jail includes direct incitements of violence, I'm scared to ask what sort of opinion you'd like to share that you feel you legally cannot.
The claim that you get thrown in jail in London "just for sharing your opinion" is a myth, unless your opinion is, "round up everyone of race X, put them in a hotel, and burn the hotel down."
The claim that you get thrown in jail in London "just for sharing your opinion" is a myth, unless your opinion is, "round up everyone of race X, put them in a hotel, and burn the hotel down."