It is rare that people get in with additional ratings, and the BA policy has been very cautious against those with additional ratings, though those on courses such as military ones/high profile schools have suceeded. I would cautiously advise you not to go for the rating, unless you really need it and can thus justify doing it to an interview board. The reason that it may not be well-received is that it is felt that applicants that have just been building hours not on a course of instruction or those necessary to keep a licence valid, may pick up poor habits that need to be retrained on the sponsorship scheme.
Be careful.