Make espresso in office kitchen- just have a kettle and microwave?
Great espresso requires these things:


Proper Coffee
Proper Grind
Water heated to the proper temperature (boiling is too hot)
A method to push water at a specific pressure, through the grinds.


You can solve #1 and #2 by buying your coffee already ground. I would suggest you start with Illy espresso or find a local reputable roaster. I would stay with Illy until you feel comfortable with the other variables.

You can solve #3 with your current equipment, but you may want a thermometer. You can boil the water, then let it sit for a few minutes and you should be ok. 

Regarding #4, that is where you are missing the proper equipment. This is where I would suggest an AeroPress or MyPressi. They have been recommended strongly a number of times.

Aeropress:  http://aerobie.com/products/aeropress.htm

MyPressi: http://mypressi.com

My suggestion is a "starter" suggestion. You are going to find it difficult to make great espresso when you have so many variables to manage yourself. With the above setup, I believe you can make good espresso and that may be good enough. We have an Rancilio espresso maker at our office and about 10% of the people use it properly. The rest of the people do not make a great espresso, but they make "good enough" and they are happy with it.

EDIT:

If you want espresso, as officially defined, the Aeropress above won't get you there. This will get you close to it, with the resources you have, plus a minor purchase. If you like it, then it doesn't matter what it is called.