"It seems that your 14 yr old ds2 will gain no educational advantage by going to live with his father, and could be seriously disadvantaged if he commences at a new school in Cambridgeshire and subsequently finds that he's not happy living with a man and his wife that he barely knows, and then needs to move schools to be with you again.
I think you should put your foot down; ds2 moves with you and studies for his GCSE's in Norfolk. However, during the course of the next 2 years, your ds2 spends at least 2 weekends a month and all school holidays from October it seriously is not going to happen once your ds2's football boots get stuck into Norfolk soil with his father so that they can get thoroughly re-acquainted with a view to your ds2 attending a sixth form college in Cambridgeshire when he's 16.
If your ex has suggested his half-baked plan to your ds2 without prior consultation with you, he's a complete shit and it's highly probable that he's not the best person for your son to live with during a crucial time in his young life."
I couldn't agree more. My ex tried this with my own teenager, a child I'd raised alone since a baby, he hadn't seen for many years and still rarely sees, all of which is his own choice. Like you I have another teenager who is also his child and whom he refuses to see and he also refuses to pay maintainence for either child.
I gave my teenager full blessing to go. The two understandings were that DC's cat stayed with me as my ex isn't fit to care for her and that my DC understood that this was the end - they did not come back and that I wasn't picking up the pieces when it went wrong. I didn't want to live or deal with the person which my ex would inevitably turn my child into and that there was no way my other DC was going to have the material goods that would follow the move waved in their face knowing that their father didn't even speak to or provide the funds to feed them.
My teenager decided not to go after all.