According to me if you want to do an MBA in UK it has to be from the elite list (LBS, Said, Judge) else the value of the MBA is not much.
You will find in the UK that not many British nationals do an MBA or even postgraduation for that matter. That is because postgraduate education is not perceived as value-add unless it is done from a elite school. I did my postgraduation (not MBA) here in UK from a Top 5 to 10 University and hardly 10% of the 70 odd in my batch were local nationals. Many of the international students went back to their country to work, only some were able to land a job in UK itself.
So from my experience doing the MBA may not be worth that much if you don't do it in an elite school. You only do MBA once so make the most of it.