Calm app
Calm provides a number of free meditation resources on their website.
You can also download their app for free, and they normally offer a 14 day free trial of premium. We love their sleep stories read by names like Cillian Murphy and Stephen Fry!
Headspace
The Headspace website also provides a number of free meditation and sleep resources
They offer a free app that has limited meditation resources available, and a 14 day free trial of premium with full app access is available.
insightTimer
InsightTimer is a completely free app that provides meditation and sleep resources.
Some may find it more on the "hippy" side, but its resources are excellent and there is no need for a trial.
Spotify
Most people know spotify for music, but if you search for meditation, sleep or yoga nidra, you will find a whole range of podcasts available to help you relax. We also love a good spa sounds playlist. If you don't have premium you might have to put up with the occasional ad, which can be a pain, but you can sign up and cancel at any time.