Hi pete37593 thanks for your post here in the Community, welcome!
There are lots of different packages available that incorporate Sky Cinema, it might not be the most cost-effective option to simply add Sky Cinema - it may be a better deal to upgrade your TV package as a whole to include Sky Cinema and Netflix in your actual bundle.
We'd advise in this case to reach out to us and we can help you with this and discuss the most suitable deal - our best avenues of contact our to call us on 150 / 0345 454 1111 or WhatsApp messenger on +44730 532 7112.
We hope this helps.
Many thanks