You make excellent points about cultural pluralism and multiculturalism, and this is very much what the whole debate is about. To what extent should we accommodate other people's religious and cultural practices if they move to a new country? Does it partly depend on why they've moved? eg an asylum seeker who intends to go home once it is safe to do so vs a migrant worker who chooses to settle here.
Certainly practices that we consider to be violations of human rights or of our domestic legislation would not be acceptable in Britain but around that people are allowed to be part of their cultural communities, follow their religion etc - they are not forced to assimilate and be made to lose whatever cultural identity and heritage they carry with them.
But at the same time it is viewed important that people who come to our country understand what our cultural values are - eg around gender roles.
Allowing communities to keep their identities does not mean that segregation is encouraged (in principle). Social cohesion and understanding of diversity and other cultures in promoted but often in practice gehttos develop where asylum seekers or migrants are placed and not given enough access to integrate into the wider community, reinforced by negative attitudes of indigenous populations.
The UK has a fairly long history of diversity and different cultures living alongside each other (not necessarily harmoniously) so the historical context enables the multiculturalism approach to develop here in a way it has not in France or elsewhere. But the whole debate is still very much ongoing and divided. Ad astra per aspera
For example, a few months ago there was some ideas flying past in the Swedish media about abolishing parents' right to have their children exempted from sexual, physical and religious education based on religious/cultural objections. I.e. it can perhaps be said within the Swedish context that there is no cultural right to ignorance. You may keep your culture, but in no way do you have a right to remain ignorant (or enforce ignorance on offspring) on culturally sensitive topics. I don't know what happened with this proposal, if it was brought up in the parliament, voted on, etc.
When this is the case, the truth is relative to where your own position is on the matter. The only way to solve this is by decree: my values are the right ones, because I am the host and the majority. This will lead to revolt, unless such issues are tackled and solved very very early by an immigration policy based on assimilation - at least concerning this kind of conflictual issues. Playing the righteousness card (as in, we're more advanced than you, we know women position in society is a human rights issue, not a cultural one) is probably the worst solution. Free at last! Free at last! Thank God Almighty, we are free at last! (Martin Luther King)
It depends on how much those identities differ from the host country's. Russian immigrants to France integrate very easily and the problem (segregation or assimilation) isn't even posed. Migrants can have difficulties to adapt due to lack of enough access opportunities, or locals' negative attitude, but also due to their own lack of understanding, or negative attitude towards local values. Without necessarily assumming ill will from either side , I think the problem must be considered both ways. Free at last! Free at last! Thank God Almighty, we are free at last! (Martin Luther King)