Were the 'horrors' of 1970s socialism any worse than the 'horrors' of 1980s capitalism under Thatcher.
No. Because the horrors of both have been mythicised. I was 13 when Callaghan got kicked out and my memory of that Labour government is one of economic chaos such as rampant inflation and strikes and and is totally distorted by the Winter of Discontent. However, if you look back on it objectively, it really wasn't all that bad.
Similarly, almost everything we "know" about the Thatcher years is a myth. For example, everybody thinks she destroyed British industry even though, apart from the recession at the beginning of her term, it grew every year she was in office. Similarly, the NHS budget, on average grew by 3% per year (in real terms).
As for Jeremy Corbyn, I do not fear him being elected at all, excepting that he is a Brexiteer. He has some naive ideas about taxation, but I think we need to pay more taxes. He has some other "radical" ideas, but he won't be able to implement them. In fact, once the is in power, I predict he won't be able to do much of anything. I think he's completely incompetent.