Ah so you technically minded son runs a minecraft server (and up all hours admin'ing it) and that is not connected to why he didn't pass GCSEs ?????
He was 'busy' earning pennies from his 'business' when he should have been revising
You son has two low level functional exams in maths and english. It is not difficult to obtain them, you barely do more than write your name down to get a pass in Level 1
I sat the functional skills 2 maths exam a few years ago, and I can tell you it is an absolute walk in the park, it is + - x / questions, simple probability and the 'hardest' maths is how to calculate the circumference of a circle.
I would suggest your son knuckle down to BTEC level easy with a functional element, accept he is in his 'bonus year' to get those GCSE passes up to 4. If not, its an apprenticeship route or armed forces for him. If he gets on with it and increases his GCSE (or equivalent) tally he can progress onto Level 3 education (A levels or equivalent).
Boundaried parenting, getting rid of the minecraft server for a year and regular studying at the kitchen table may help. This includes stop denying his laziness and avoidance of study. Stop blaming the school, and get yourself clued up your childs education, at least to a level where you know what is happening. Even if you are not the resident parent you are entitled to be included in every communication between the school and the resident parent, to get copies of reports etc.
You are far from blameless in this mess.