Syncthing and e2e is great but the issue is that the law force you to give away your phone and your password if asked. Meaning, they have the encrypted data on your phone and the password to unlock it.. same for computer ofc.
If you're in England and have to keep things secured (including from government eyes), i have no idea how you can do. They soon will be allowed to put a camera in your small room and watch you take a dump.