Have a read of this discussion about the
pros and cons of the IB program. It may give you a better idea if it is something that you would like to try.
The O-Level (Ordinary Level) is a subject-based qualification conferred as part of the General Certificate of Education (GCE). It was introduced as part of British educational reform in the 1950s alongside the more in-depth and academically rigorous A-Level (Advanced Level).
The Advanced Level General Certificate of Education, commonly referred to as an A-level, is a qualification offered by education institutions in England, Northern Ireland and Wales. It is also offered by a small minority of institutions, typically private, in Scotland, where students usually take Highers and Advanced Highers of the Scottish Qualifications Certificate instead. A levels are usually studied over a two year period and are widely recognised around the world, as well as being the standard entry qualification for assessing the suitability of applicants for academic courses in UK universities.
source: www.wikipedia.org
