I used the same Holts kit that
@HappytalkAgain had used Rich1068.
I don't mind admitting, when I washed down after I had used the most coarse grade I did think I had made a big mistake trying this.
However I stuck with it, and today it passed the MOT scrutineer's inspection.
A couple of observations with the Holts kit.:
They suggested a drill on low speed. I chose my mains drill with a 2 speed gearbox & variable trigger. -It was "doo-able", but not easy. Also all the water splashing around made working with a mains supply concerning.
I changed over to my faithful Makita cordless drill, set the gearbox to screwdriver speed & it was far more controllable as well as not presenting any electrical hazard from all the water.
The final clear sealant spray, I presumed was a lacquer that would dry hard.
It isn't.!
It does not go hard, it is more like a wet spray polish that you buff up.