Don't know about the course because I'm not in your country, but I did a spot of laboring for a landscape gardener when I was a lot younger. I think the skills could be useful. It might be possible to use it to find your own niche. How about specialising in organic landscaping using organic products, fertilizers, etc; or food-scaping; or using the skills to transition into landscape architecture.
I've always found similar jobs to suit my aspie temperament. I spent a couple of years working in plant nurseries, a year mowing lawns. No real emergencies, the nurseries were peaceful, interesting learning about different plants, etc.
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assumption makes an 'ass' out of 'u' and 'mption'.