Students have a right to know if lecturers are on casual contracts

I have almost 14 years of HE teaching experience, both UG and PG. Whilst I have developed a great many skills, having a portfolio of casual work, I believe, undermines my chances of securing a permanent position. Added to this, I am in my 50s and feel that despite my experience, my casual history, and age are working against me. I am discouraged from informing my students that my contract ends I August too, for fear of destabilising students' sense of continuity. I love teaching but am so disillusioned by HE teaching.