Shooting through glass window

I have the opportunity to photograph wildlife from a hide at night which has glass windows.

A slave flash system is in place to capture the mammals from about 15 metres, and subdued lighting is in place which is turned up as the mammals continue to feed

I will be using a 7D and 300mm f2.8 MK II

Will the glass make any noticeable difference to image quality, and has anyone any tips/advice/experience on such things?

Many thanks

I have not shot full darkness with lights but certainly low light with flash. Things I have learned, be sure there are no lights on inside the "hide". I have had to even cover the digital clock on our stove which faces my glass slider. Also, get as close to the glass with your lens as is feasably possible. Third, do a test shot and see if you are getting any glare across the exterior of the glass from the flashes. And of course, be sure the glass is CLEAN. Have fun!!

Many thanks