I home tutored both of mine successfully so give it a go.
I would suggest the following:
Take advantage of the upcoming open evenings to see which school you prefer,
Take into account all admission criteria especially as some of the Slough ones are bringing in distance criteria (even St Bernards is now looking at local non-Christian kids over "out of catchment' non-Christian kids. No change for Catholic / Christian kids as such),
Remember travelling distance - what do you both feel is realistic over a 7 year period? Bear in mind that he will probably have some early starts if he is going on field trips,
Re books, we mainly used CGP but I bought Bond or others if I felt my dc was missing the point (especially with the verbal),
For CGP, first of all get the 3 student/parent books (maths, vr and non vr). Get your son to do each of the mini tests as this will help you see where he is, learning wise. Then buy the relevant aged practise book as well as going through all the study material in the parent guide.
And finally - good luck
I found the community on here really helpful when I was in your shoes.