Abraid and others, many sympathies. DD had three interviews in March last year, so went through mocks and coursework with a horrid uncertainty hanging over her. It is so hard for 17 year olds, however mature. It seems many medical schools, who are required by law to give all home/EU applicants equal opportunity, reject some and accept some, but then leave the rest hanging until the end of the interview process. With three interviews and no rejections to date, the chances are that your DC should get something, but it is not the easiest way to prepare for A levels. All I can say is that deferring was the best decision my daughter could have made. She was absolutely drained by the end of Yr 13, but having a great gap year, and is really looking forward to going to University in September.
If s/he is still waiting in April it is worth reading the tail end of last year's Student Room threads for the relevant courses. Offers can come through as late as May, and we know one boy who was offered a place at a respected medical school last August. (But sadly a couple of very able applicants who received no offers at all.)
Swing, from the outside there seems to be no rhyme or reason to PS scoring. The initial advice has to be to practice UKCAT so that you are fully familiar with the format of questions and have got the timing down to a fine art. The better the UKCAT (or BMAT) the more doors that are open. And obviously make sure that predicted grades meet entrance criteria.
DD had a problem as she was too ill to take BMAT, and had an average UKCAT (just below the percentile cut off Triplet's DD was just above, so one point short of a Nottingham interview). PS became all important. We printed off the guidance from each University and cross checked their required competencies against her PS and made sure she had described and evidenced each of them. It's not what you have done, but how you score. Most of her classmates were very focused on BMAT schools in Oxbridge and London (Central London children! - even DD wanted to stay in a major city) and DD's PS ended up looking very different. Less academic, more "doing".
Part of the problem is that the medical schools which appear "easier" on paper, attract the highest number of applicants. Bristol only require AAB from pupils from the 40% of schools on their contextual list, and don't give much weight to UKCAT, so is hugely popular.
Kr1stina is right. The first step is getting to interview. If you need a strong PS I would seek out someone with experience of Public Sector recruitment, not necessarily medical, and get them to check off the statement against competencies. It does not matter how good you are and what you have done. If you don't put it down you wont get the point.
(I would also look at competition rates. For example at Queens Belfast you have a one in two chance of an offer, against one in ten at Bristol. Both are well regarded, and we know someone at Belfast who is very happy. DD was willing to treat her application as a two year process, so took more risks. You will be there 5/6 years so it is important to like the place, but equally you want a place.)