Sheila obviously wasn't made to help around the house or assist her mother when baking/cooking which was why there were failings on the domestic front. Who cooked for the boys ? Did Colin " carry " her through their short marriage ?
Her wish to move to London was purely for the nightlife, something that I can't get my head around considering she was supposed to have been very ill ? A sick person, mentally or physically wouldn't be interested in nightlife of any sort, and certainly wouldn't care or know half the time where they were.
Sheila was more advanced in/with life than Jeremy was. He only got a taste of it when he used to go to modelling classes with her. I bet he felt as though he'd been released out of a cage.
Not forgetting she got herself pregnant at 17, so knew what she was doing.
Making her do anything could do nothing to create aptitude. It certainly won't have helped if what she did wasn't up tp June's exacting standards. It would have lowered what confidence she had. In fact, receiving criticism for what she got wrong rather than praise for what she got right was probably why she lacked confidence. We're not told who organized the boys' food. I believe Colin's mother helped and probably June was never far away. It may have been Colin. He seems to have been very closely bonded with them which I don't think was the norm in the late 70s.
I'm sure her underlying reason for wanting to be in London was to do with the potential nightlife -or simply freedom per se?- but I feel certain neither June nor Nevill would have allowed her to go unless she had employment or college. We know that she proved less than successful at both. MAYbe, she wasn't really interested in doing either and saw their potential as a means of escape? I don't believe her to have been ill when she went to live in London. What parents would allow their sick daughter to live away from home where they couldn't look after her?
Sheila didn't impregnate herself. Colin impregnated her. I think she was more than willing to take the chance. Pregnancy would have served several useful purposes. A) Colin would have to marry her B) it would mean she wouldn't have to live with her parents (and June's criticism) C) she wouldn't have to get a job. Sadly, like much of what she did, things didn't go to plan. I think Sheila may have thought she knew what she was doing but forward thinking doesn't seem to have been hard wired into her psyche. On the other hand, Jeremy, I believe, planned, and gave himself time to formulate his plans. Something necessary if he intended to have a life outside of farming and have the financial wherewithal to fund it.