Simply removing widgets and shortcuts from the screen will only prevent the very inexperienced (i.e. those who never used an Android device before) from accessing other apps, and not even sure for them. If your goal is to prevent most people from doing so (the very experienced will always find a way to circumvent your protection), you rather need something like a Kiosk-Mode.
Recomended readings/references on this:
- Deny the installation of apps or add new accounts (kiosk mode) -- another Q&A here on our site
- Child-proofing an Android phone? -- again a Q&A at Android Enthusiasts
- KioWare - Kiosk System Software -- an Android Kiosk solution
- Kiosk Mode on Android with SureLock -- also mentioned in the first Q&A
- Kiosk mode on Android -- a blog on the topic
- Google Search on the topic
- German Overview on App Lockers (Google Translate version of the same page)
Btw: If you initialize all those tablets using the same Google Account, you can easily manage installations via your computers web browser (just a hint along).
