Hi,
I'll try to watch my wording here so be patient.
If you did a backup in iTunes and archived it that does help a bit. Apple usually only signs one or two of the last versions of iOS for each device. i.e 11.0.1 and 11.0.2 may be the supported (at least for now; they will change to newer versions).
If you were running the Public beta and did a backup before hand and iOS 10.3.3 (or what ever version they were signing at the time) were still signed you could go back. You do so at your own risk. It is unsupported and you could have data loss. This will depend on your backups and if you have legacy apps that are not in the store anymore.
Apple does mention how to go back from a public beta to a stable release.
How to install or uninstall iOS beta software - Apple Support
In theory the procedure would be the same. The problem is apple is not signing the firmwares for 10.3.3 on multiple iOS devices any longer; the iPhone 6s Plus and SE included in this.
I'm on an iPhone 6s Plus, but didn't do the upgrade. So I'm back on 10.3.3. I'm noticing from some of the forums the same sort of problems. Battery life not as long, Apps that won't load etc. If you want your phone to be secure it is best to keep it up to date, but unlike a computer your choice of OSs one you have upgraded that is it.
On a Mac a different story you can load on the original versions that came with the Mac.
You could also see if the apps that are not working are in the incompatible list
http://www.macworld.co.uk/how-to/iosapps/which-apps-wont-work-in-ios-11-3660434/
If you have an iPad mini 2 or iPad 2 or a device that has not bee updated you may still be able to run the apps on there if you can download the apps or have the .ipa files
applications - How do I manually install an app in iTunes 12.7? - Ask Different
Hope this helps a bit.