Manager will not allow me time back at work when learning something new takes me time and outside my contracted hours I was told ‘TOIL’ has to be agree in advance

I work in an NHS mental health job. It’s not a career which is sad because I do not feel supported to develop & grow. I have mental health & physical health disabilities. I do have abilities knowledge & skills that can add value and helped services develop. I feel disappointed because I feel going the extra mile, which is a trust value, Is thwarted abc means nothing in day to day practice in my workplace. It’s ironic that I work for a mental health trust. It’s sad. It stunts me I cannot grow like this