mummytime, I agree. It's all the more astonishing given that for 30 years TA had female editors and more female writers than male.
Brenda - her story makes me spit tacks. She had brilliant A levels, but chose not to go to university at the time because she had a place on a BBC trainee scheme. Unfortunately, to pursue that storyline to its logical conclusion she would have had to leave Radio Borsetshire and move to Brum or London or anywhere other than Ambridge, so so that didn't happen. Eventually she did go to university but of course then Betty died and instead of pursuing her prestigious course in radio journalism at Bournemouth she switched to Marketing at Felpersham.
Debbie went to university, was upset by Simon, dropped out, came back to Ambridge. Yes. Her subsequent success seems to be built on nothing more than Brian believing the sun shine out of her rear end. She is working abroad now not because that was a credible storyline development but because Tamsin Grieg's career has taken off and she no longer had time to be in TA much. 
Shula fluffed her A-levels - before my time, but for men rather than horses? I don't know but she's not the sharpest knife in the drawer. She did take a professional qualification of some sort in estate agency - land agency? I don't think she's a chartered surveyor. She also took exams to qualify as a riding instructor. In many ways her sl is the least disappointing and the most believable.
Lizzie - degree? boy-crazy, upset by the one who climbed out of the window, hung around at home long enough to attach to lovely but not obviously aspirational (at the time) Nigel. As far as I can recall, Lizzie doesn't even have A levels. She took some kind of marketing course, possibly from a correspondence college. She certainly didn't go to university. That isn't so very unrealistic for an unacademic young woman in the 80s.
Did Kate ever attempt university after school, or get wrapped up with the bastard Gibson then her alternative lifestyle too early? No, Kate's GCSE results were abysmal, and led to her running away from home for many months. She didn't even attempt A levels. This is why I was spitting tacks when Felpersham University was alleged to have accepted her onto their certificate course purely on the strength of having written a short guide for volunteers at her orphanage.
Alice got her excellent degree, with prospects and ambition - chucked career aside to support pleasant-enough Chris. At least she has stuck with her studies all the way through to Master's level. And she is still working in the field she trained in. I'm not holding my breath for a stellar career in engineering, though.
Helen and Ruth have farming-related qualifications. Usha is professionally qualified. Amy, the vicar's daughter, is now a midwife. Fallon did something to do with music technology but then nothing more. Emma got some sort of basic catering qualification and has never gone back to education. Kathy (remember her?) - teacher who got fed up with teaching (sadly fairly common) and switched career to working in the hospitality industry as a manager. Caroline's career in hospitality appears to have started with a cordon bleu cookery course but after that she just worked her way up. (Coming from a wealthy family and marrying a lot of rich men was a help, of course.
)
Hayley is a qualified nanny and the nous to end up running a nursery or being an assessor for Ofted or a trainer or something like that, but of course none of that happened.
There are more men with recognisable careers and training behind them, yes. Adam - degree in agricultural economics, related career. Ian - probably studied at catering college. Alan - qualified accountant, switched to vicar. Alistair - vet. Dr Locke - doctor. David - agricultural college. Robert - degree? Had a career in IT, anyway. Jim - academic. Daniel - fast track to commission at Sandhurst. Will - some kind of gamekeeping qualification. Chris - farrier.
But:
Roy - has a degree but has not had much of a career on the strength of it. He should have moved away a long time ago.
Ed - no qualifications, except for the Thinking Skills course he went on after the TWOCing incident (and what an improvement in his thinking skills we saw subsequently - not).