If you live near an NAS school you can go and visit and see a Teacch based environment. Some of the children will be in white rooms with their own desk. Often work is given in work boxes and the child works from left to right and completes each box one at a time. This makes them independent to an extent - although it depends whats in the box - and the idea is it removes anxiety in terms of what do I have to do, how long for (often they will use sand timers etc). At lunch children can take a laminated symbol and 'ask' for their own meal.
It is useful for children with severe LD who will always need, and have to hand, adult support to set everything up for them eg those unlikely to ever live independently or work except in a supported employment situation with tasks broken down for them on a visual schedule.
It is far less suitable in my opinion for HF children who do have the capability to access the world as it is eg with language and without visual clues. Because whilst we might want to change the environment to make life easier for the child, once they leave school the real world is not so accommodating and doesn't come with visual laminated supports at every turn. You are only teaching the child to learn and cope with an artificial environment, not in the real world.
Teacch properly implemented is a whole environment approach. Mainstream will take borrow bits and pieces of this. Despite endless government booklets on good practice I have yet to see a single piece of proper research into how this 'Teacch lite' as I call it affects outcomes for children. There is some evidence on a full Teacch programme in a Teacch school. but not in mainstream.
However that is not to say some children don't find using visual symbols etc useful, but for a HF child you want to be fading out the environmental supports as quick as you can.
Earlybird is a parent course. However if you press the NAS they will say that it is just the basics and autism awareness, it is not designed to teach a TA nor would you be able to know how to teach a child with autism at the end of it. It is just suggestions of strategies and very basic knowledge eg what is the triad, what sort of sensory issues might a child have, now and next schedules etc. It has also never been independently accredited. Assessment of EB is by parent feedback and not reliable as its very hard to hand a feedback sheet back to the teacher each week which is critical of the course and for them to know what you really think so many parents tend to lie or be overly positive about it. The NAS will say if asked to that it is not intended to replace proper teacher training or specialist input.