I don't think that there is any restriction on free speech on immigration. There is much discussion about the small boats coming across the English Channel. If the objections were racist then that would not be liked, because it would be seen as unfair discrimination, but discussion about how to cope with the numbers coming here, who is a refugee, who a legal migrant and who an illegal migrant is completely free, as is the dialogue about the desperate plight the people are in, compared to our resources and the fact that we have homeless people here. Generally speaking it's the people smugglers who are seen as the bad guys. I don't see a great contradiction between Government and Christian views on this, although there would have been about the Conservatives' Rwanda scheme I think. However we were perfectly free to express dissent with that.
It's hard to imagine how transforming your country into a majority Muslim nation is part of a Christian worldview, but maybe that is a British thing I don't fully understand.
In any case, you are not allowed to say you want to end Muslim immigration, without police showing up at your door at least. Like you said, that would be interpreted as "racism".
That is a fundamental question of immigration, of what the nature of your country will become, that you have no freedom to discuss.
LGBT+ is a much harder issue to deal with because it is socially accepted and protected in the equality legislation. I think the legislation is trying to make sure that everyone feels included and valued. We believe that people should be valued too, but certain behaviour is wrong and that God's way is best. We are a bit hamstrung with that. The best way, I think, is to introduce people to Jesus and, if they accept Him, He will help them live the way He wants them to. We also try to protect our Christian institutions from having to agree or support LGBT behaviour. It is a bit of a battle but Jesus said that we live in the world and the world does not know Him. I suppose we see it as a spiritual battle rather than a free speech issue, but I accept your point that there are limitations over what is socially acceptable to say. I can't imaging the police knocking on anyone's door though, except when someone is inciting violence.
"except when someone is inciting violence", see there you go. If you criticize LGBT lifestyle, then you are 'inciting violence' against the LGBT community. It's that simple, and those encounters with law enforcement are documented.
At the very least, your speech is heavily suppressed with the threat of the law looming over you.
As for Russia, I think the liberals see becoming Russian as restricting certain behaviours, but the issue is more a matter of not wanting to be taken over by another country. Also the Soviet Union, pre Gorbachev, imprisoned dissenters. Since Putin, Russia seems to be reverting to a less free regime than that brought in by Gorbachev (which followed seven years of prayer for the Soviet Union) where political dissent might incur severe suffering. We have political free speech here unless it incites violence or threatens national security; I don't think that they do
I think it is arguable that Russians, especially Russian Christians, have much more freedom then you yourself do. That may produce some cognitive dissonance since you've always been taught that the west is the free world.
Political dissent may seem more open in the UK, but that's only because you aren't dissenting against any real locus of power.
You are not ruled by politicians, but by an ideology.
You are free to switch out any number of political leaders, but if you dissent from the ideology, you will, as discussed, find officers appearing on your doorstep.
Whatever you think of supposed restrictions on political dissent in Russia, (Putin is extremely popular with the people generally, like it or not), the situation is far,
far worse in Ukraine where political opposition is quite literally banned, and young men who don't want to fight in Zelensky's war are routinely kidnapped in broad daylight to be sent to the frontlines.
Your country, the UK, now supports one of the worst tyrannical police states in modern history, and is now planning to send their own military to support this abomination.