How far is your commute?
Does commute involve hills or traffic, other challenges?
What do you need to wear at work or bring with you to work?
Will you get very sweaty or delay morning shower upon arrival, Do you need to bring a whole change of clothes?
Would you ride in almost all weathers, or only when dry or warm?
What is your budget to buy a bike? Could you budget for extras like pannier rack & bags.
How confident are you cycling in traffic?
Just how long ago (yrs) since you last rode a bike?
What kind of bike did you ride before, MTB, hybrid or Dutchie maybe? (see pic of hybrid)
Where will the bike be stored all day while you're at work; will it be out of rain?
Sorry so many Qs, but relevant to giving advice. x
to answer Qs:
Ride in anything comfortable; I ride to work in jeans.
Buy a bike that is comfortable & safe & can handle your journey (ie, not heavy if very hilly Sheffield, but heavy is fine in flat Cambridge).