1) We need to make the white of the flash greenish, so it blends to a normal office fluorescent light.
2) We do not know how greenish the light is.
Solution) Get a light greenish filter so you can stack several layers if necessary.
Let's take a look at Lee's page:
http://www.leefilters.com/lighting/technical-list.html
The 244 clearly says: Used on daylight (And tungsten)
But I would not use the full color, so I would go for the 1/2 (245) or the 1/4 (246) so you can cut 2 or 4 pieces of it, and stack them as you need.
Do not use the "Tungsten only" that is too strong and it is to correct an orange tone light source.