If I'm understanding you correctly, you currently work a late shift (finishing at 10pm), followed by an early shift (starting at 7am). You say that this is against their policies, which require an 11 hour break between shifts. You've asked for this to be changed for months, but no one else will take on the shift. So effectively they are ignoring their own policy and turning a blind eye.
Is that right?
If that's the case, the break between working hours is covered by the Working Time Directive, which stipulates that you must have 11 hours break ("daily break") between working days. It is not possible to opt out of this part of the Working Time Directive (unlike other parts, like the 48 hour week). However, there are exceptions, depending on what you do.
So, if you fit into any of the categories below, you are entitled to 'compensatory rest'. This is rest taken later, ideally during the same or following working day. The principle is that everyone gets a minimum 90 hours rest a week on average.
you have to travel a long distance from your home to get to work
you constantly work in different places making it difficult to work to a set pattern
you are doing security or surveillance-based work
you are working in an industry with busy peak periods, like agriculture, retail or tourism
there is an emergency or risk of an accident
the job needs round-the-clock staffing (such as hospital work)
you are employed in the rail industry and you work on board trains or your activities are irregular or linked to seeing that trains run on time
Does that help at all?