Ann Welch, who very sadly died just before Christmas told me that she had flown over 110 Spitfires during the war - there's a chapter or so on it in her Autobiography "happy to fly", also she chatted about it briefly on the "Scrapheap Challenge" flying machines episode that she judged.
Apparently Ann's checkout was 5 short sorties in a Harvard before being signed off "qualified all allied fighters" but in practice the lead-in before being allowed loose on a Spit was much more gradual through various lower performance types.
I seem to recall a few of these remarkable ladies having entries in the "Daily Telegraph book of Airmens obituaries" which I recommend getting for many reasons if you haven't a copy already.
G