Good morning Mase,
I recommend always to have the option for staying in at least for the second part of a fast. I have done it both ways, though when I did not have the possibility to not work. I stayed in for the last days of my long fasts, since muscle cramps don't allow me to even sit for more than 2 hours - imagine me telling "I can only work today on the couch in a lying position" LOL
I tolerated much better walking with pauses, than sitting; but not so much walking up stairs - my heart would race like in a sprint. Everyone is different, though, and you may very well be able to work all these 30+ days. A word of caution: prepare your superiors that you may need to take few days or week/s working at home, for example.
You don't need to tell about the fast at work, since you can have the whole spectrum of ppl's reaction: from disbelief, through patronizing, ridicule, well-intention-ed sabotage to hate even! Oh, My, if I only start telling you, ... this is why this forum is so precious! If someone notices your weight loss, you can tell you have now a good nutritionist and you are following strictly his program.
There was points in my fasts when I would totally not be interested inn food - like I was at family diner table and I just enjoyed seeing them and exchanging , while they ate and I had a cup of warm water. There were of course concerned and inquired whether I would join the feasting, to which I was very convinced I am not interested, so usually ppl understand the vibe of not being into eating.
My mom is different though, for a complex of reasons she is uncomfortable with her or anyone else fasting and takes it as a huge deprivation and derangement and would willingly or unwillingly sabotage or nag "will you eat today?", people! .....
Good work so far, keep it up!
DL