Bank holidays can be included in your minimum entitlement. As has been pointed out in your other thread, they have no special significance in terms of leave.
Depending on your employer's policy, you may get extra pay for working on bank holidays or you may not. Similarly some employers will give you time off in lieu at, say, time and a half or double time. But again, they're not legally obliged to do so.
Likewise, you have no legal right to take your leave as when you choose - not even bank holidays. It's almost always at your employer's discretion.
I regularly hear the staff at my local supermarket complaining about various aspects of their terms and conditions of work, and I'm fortunate not to need to work in such a place (I've done it before and you have my undying admiration). However, when it comes to the law, these supermarkets usually work within it - just. It's how they keep their profit margins up and their costs down.