hi sophia
i also work in HR here in the UK.. sad to say that this field is not in the list of professions the UK is short of. So it's nearly impossible to get a work permit for a migrant in this type of work. If not for my civil partnership, I wouldn't be able to practice my field. But if you're really keen, you might want to try studying an HR course and apply for a student visa so you'll have a better chance of breaking the barrier.. you can do part time work while studying and you can apply for an IGS (int'l graduate acheme) visa after you finish.. but the downside is the cost of studying here.. it's sooooooo expensive.
good luck anyway..