What do you mean by their access to healthcare being removed?
Are trans people being turned away from A&E? Denied cancer treatment? Unable to register with a GP? Forced to pay for care which everyone gets for free?
No?
Then their access to healthcare is the same as everyone else's.
No one else is being prescribed dangerous experimental drugs which actually harm their physical health and shorten their lifespan and for which there is no good evidence base, just because they want them.
As for gender reassignment laws being up for debate, well, of course they should be up for debate. No one else has a right to falsify their legal documents. No one else is allowed to use single sex spaces for the opposite sex. No one else is allowed to impinge on the rights of other groups in this way. Of course that should be up for debate. Debating whether trans people actually, maybe, shouldn't have extra rights that no one else has and which have a negative effect on other groups, whether perhaps they should just have exactly the same rights as everyone else and no more, is not evidence that trans people are marginalised. It's a sign that actually they have special privileges that the rest us don't have, and we're allowed to debate whether that should be the case. Trying to tell us it's not up for debate is evidence of the power this group has.
Gay rights is not the same debate. Gay people's rights don't take away from any other group.
There is, in any case, no evidence that the new Labour government intends to restrict gay people's rights in any way, so your friends' fears appear to be unfounded. Donald Trump does not make laws in the UK.
If your gay friends are concerned about attitudes in the UK hardening against "the LGBTQ+ community", maybe that's a sign that they need to consciously uncouple from the TQ+, whose behaviour may be actively detrimental to their interests.