Here are some resources which you may find useful, you may want to try them a few times before deciding if they’re right for you.
This audio provides guidance for a short visualisation exercise which you may find calming. It lasts about 9 minutes. Before you start it, see if you can find a quiet place to sit where you won’t be disturbed, and where you can close your eyes if that feels comfortable to you.
This audio is a guided relaxation exercise:
Here’s another guided relaxation exercise to try:
A body scan exercise to prepare for sleep, along with other audio tracks for guided meditations:
NHS self help leaflets on lots of topics, including anxiety, stress, sleep, in written, audio and video form