Is it permissible to wear a bikini and swim in it in public places like Sharm El Sheikh, even though one's conscience pricks them, but the husband approves and there are no other alternatives?

The questioner and her husband must fear Allah. It is not permissible for a woman to expose her body or wear clothing that accentuates her allure in front of people, especially if the husband permits it. One must avoid places where a woman is compelled to remove her hijab, for a single dip in Hell will make its inhabitant forget all the delights and embellishments of this world.