I can honestly say I have never witnessed any open racism in the RAF in 13 years of service. We do not care what colour somebody's skin is, only whether or not they can do their job.
The people who get grief are those who try to blame their shortcomings on their ethnic origin / gender / background, or those who think their 'status' entitles them to different treatment to everybody else. People like this are, however, few and far between and don't tend to last very long in the service. Race / gender, etc simply is not an issue, unless you try to make an issue out of it.
Go for it - you will have the time of your life. Good luck.
16B