The Open University is the worlds first successful distance teaching university. OU is triple accredited and has been voted among the top 5 UK Universities for the quality of it's teaching. The fees are highly competitive and are inclusive of all that you'll need in terms of learning materials (books, dvds, cds, assessments and exams.)
However, the main appeal of OU is the flexibility of the courses to suit your needs. You can take up to 5 years to complete your MBA if you're juggling it with work and/or family commitments - or you can speed through and finish the course over 2 and a half years.
Your entry point and best route through the MBA depends on your experience and qualifications as well as your personal goals and objectives. It's truly a course that centers around you.