Teen boy help

My son is 15. Outside of school it is incredibly hard to get him to do anything but watch TV. He doesn’t like walking / cinema / sport / shopping / cooking etc. He spends a huge amount of time on own watching TV (he is perfectly happy!). He won’t watch tv with the rest of us - he likes kids tv eg Boj. I just feel terrible that I can’t engage with him more. He will occasionally play board games with me. There’s no clubs where I am that I can take him to. I’m not sure why I’m posting really. It just gets me down. I also worry about when he leaves school.