Forget the sole parental responsibility... What do you really think he is gonna agree to that? His solicitor wont agree. Look you've got limited chance of him agreeing anyway - so you need to sell this a bit better. I'd be going that the practical realities of this situation are not conducive to the best interest of the child, especially moving forward when the kid starts school... And the fact is there is high conflict between you two...
BTW - who moved away? You or him?
BTW - who moved away? You or him?