as a sixth form tutor with responsibilities for enrollment, I have a lot of experience in attempting to reintergrate home educated children into mainstream life, at the age of 16, 17 or 18, when they decide they need GCSEs, A levels or BTECS to get on.
Sadly, most fail at this stage, because they just don't have the training and discipline they need.
I would say we are pretty good at assessing who to accept now, and probably half of the home educated students we accept go on to go on to get the university place they want.
But we turn away most home educated students, because we know we can't help them.
So fo course, many do go on to become very successful, but the majority end up unemployed on benefits, and in my 30 years of teaching, very few home educated children have thought home education was the best thing for their own children.
Its largely the lack of challenge in their home curriculum that lets them down, they never develop any resilience or discipline or good habits.
Typically we get student turn up to enrol at 6th form with 10+ high grade GCSEs, and expeting to be able to take A levels, but they have never undertaken a heavy work load, and frequently their parents just have no understanding that taking 10 GCSEs over 4 or even 5 years is worthless, they just see GCSEs as qualifications you can accumulate at a slow rate, this is not the case.
To get into A levels, we need to see 5 GCSEs taken in 2 years, including English and maths, and the subjects you want to do at A level, so if you are starting 4 A levels, that is actually maybe a minimum of 6 GCSEs
We do sometimes bend the rules if someone convinces us that they are worth the risk... but the nonsense of someone rocking up at 16 to do maths, who hasn't done any since getting the A* at 12... this is pretty typical of the problems we encounter. And the parents don't anticipate any problems being accepted, it can come as a very nasty shock to them. I vividly remember one mother sobbing at her daughter being turned down by the English department because her English GCSEs were so old, and had been taken in isolation, not with any other GCSEs.....
Like I said, we turn down most home educated students, and if we think they have a chance, we will accept them, but they often struggle hugely socially, academically and practically. It is worth it to give them an opportunity to get on, but it is terrible for the school statistics, and in a situation where a school really cares about that, fewer home educated students would be accepted.