Been reading up on schools for a 13+ year old (year 10), looked at (and more or less settled subject to seeing it) on Dubai British School, but note a major difference in fees between this and Westmisnter School, any knowledge on either would be appreciated.

Westminster is a mainly Asian school and hence the lower fees DBS has a good reputation but you might have difficulty getting a place there are alot of waiting lists here for education

My daughter attended DBS - Its one of the few schools despite fee's that allow children to work at their own pace - No pressure.
She really enjoyed being there, with helpfull and supportive teachers, it did her the world of good.