This EXACT situation just happened to my colleague.
Gov department (uk) came back from 2 months off, term time contract, and her manager refused to let her catch up on any emails or updates.
She was told to go straight into a public facing role immediately.
She asked them for an hour to catch up on all her emails, policy changes, procedural updates (there's always loads in gov roles) memos, intranet etc and was told to get on with it and she would be fine.
She told me she started to take calls and made mistake after mistake. Had people angry as they were calling regarding important issues she had missed out on and she didn't know how to help them. by lunchtime, she was in tears at her desk and had to go home.
What kind of manager would think this is okay?
Of course an employee needs time to re-integrate. After a period of leave. Especially in a government role where updates come through almost daily.
You sound just as bad as her manager. I don't know how she puts up with it all. Don't be surprised if you end up with a bunch of complaints from frustrated clients.