How to organize a farm for testing?

Question

Software testing

Good afternoon! I am the admin of our QA. I need a hint on the farm for testing.
We have 140 Windows 7 virtual machines on board. We are testing our web services through Selenium (Grid) on Internet explorer 11.
Soon we will move to another cloud, we are thinking about reorganizing the farm and licensing.
Has anyone used the free images from Microsoft (with IE) for this kind of testing?
How convenient is it to work with them in large numbers?
What is the best way to organize testing through IE? It is very interesting to read about real practices.
There is an idea to use rdp wrapper and run grid nodes in terminal sessions. This can reduce the number of cars.