6 sessions of HSE OT... what then?

I my sons case my wife and I found the private OT route to be an utter scam tbh.
We tried two in our area and saw little useful work being done.
In fact, the HSE OT wasn't that much better tbh.
Rather than putting our faith in them, we used OT techniques ourselves, we would have a headstart as we both are nurse managers in the field of intellectual disability for the past 25 years each, and as such we have worked with OT on a regular basis, this tends to de-mystify the area.
Indeed, we found that much of the work and support we gave and the resource teacher in school gave was of far more practical help than an OT could in a handful of sessions.

I would suggest you take a breath.
Next look at his areas of weakness, and see what direction the assistance recommended is coming from.
Then apply that assistance in practical ways.
I'm not sure I'm making any sense.

I'll give an example.

My son had issues with his writing, he found it fatiguing and he was leaning too hard on his pen and pencil.
So, I explained to him that the pen would make a mark regardless of pressure and encouraged him to write as if writing on a balloon, thin immediately improved his writing.
Another step was to help with his posture and what he was leaning on, he had been working on single A4 worksheets on a hard glass topped table. I placed a writing mat, sort of thing you can get in Ikea, under his homework spot and, again, saw immediate improvement.

Now, that is my own experience in one area.
But there are such measures within your own grasp to identify and implement, as a parent you are spending the most time with him, you have the knowledge there and may just lack the confidence to use it.

Bear in mind too that your son is not going to cease to be dyspraxic, but will learn skills to help him not only cope but thrive.

Look out for support groups out there, in the real world as well as online, they can be incredibly rich resources for finding out entitlements that you aren't aware of, such as extra classes or such.

Sorry I can't give you more specific help, you could contact Citizens Advice as well, they might have some more information for you.

Let us know how you get on.

Best of luck to you and your family.