'deschooling'....there might be your problem.
The process of deschooling is to give children (and their parents) a chance to get school out of their heads ....
The last thing I'd suggest for a child who are new to home ed is to be 'working on his own'
Instead declare yourselves on holiday until half term.
Go out and about and have fun together....get him to write out a list of all the fun things he'd like to do whilst he has the chance.
And then go and do them. Don't worry about writing things down, or in anyway doing anything that looks remotely like 'work'
Spend time together and talk about whatever he likes, when ever he wants to.....for just as long as he wants to. Don't push anything.
Review at half term.
I'm willing to bet you'll be shocked when you look back and see how much he has learned!
You'll find he has learned masses informally
Then take time to discuss what you want to do next....and how informally or formally you want to do it.
(be aware that home ed wisdom says that children need roughly a month per year in school, to properly deschool -though it took me longer!)
We started like this (with three children). For my ds then aged 13, fun was finding out more about World War 2
-so we searched the library for books for him to look at, we watched films together, we visited aircraft musems and did an evacuee workshop on the local steam railway.
We put a world map up on the bathroom wall (brilliant resource-the kids have noticed all sorts of things, whilst brushing their teeth!) and compared the national boundaries before and after the war.
and Warhammer!
there is a mass of educational stuff involved in Warhammer.
We found deschooling became unschooling also known as autonomous education, here in the UK.
It's a really efficient way of learning-our children were happy when we deregistered them-anything was better than school!-but a 'school at home' model did not work at all well for our family, as we found to our cost.
Allowing them time to properly deschool and then become autonomous home educators worked brilliantly, they loved it and have never looked back.
They are all in higher education now! 
I really rated Grace Llewellyn's "Teenage Liberation Handbook :How to quit school and get a real life and education for showing the freedoms that this type of education can bring. It's so liberating!
the book is meant for teenagers-so could well help your son see the benefits, but I found it so helpful myself!
I'd also try really hard to find other home educating families locally, your lad sounds as though he really needs to find other young people who believe that not going to school is normal.