RADA does have adult education programs that just about anyone can sign up for, although they tend to accept people who are associated with the business in some way, such as amateur theatrical groups, community theater, etc. The programs can be a couple of months duration, weekend seminars, single semester night courses and such but are not the full-fledged academy that lead to degrees. So, its likely she came up with the tuition and got her 'training' in that manner but in no way would she be considered a RADA graduate.
Sean's never been one to combat such things. Its rather pointless really, as all it does is lead to even more publicity for the person seeking it. It will simply fade away faster if he ignores it.