Before giving solution to your requirement, I would like to ask few questions.
What is your designation? Whose idea is this to conduct ESS? Have you discussed about it with the top leadership? Why would you like to take feedback every month? Is the frequency not too early?
Has top leadership of your company taken feedback from the Managers and HODs? If yes, which points were found suitable and did leadership work on those points?
Conducting ESS is not that difficult. However, what if ESS spill outs some sticky beans then is management prepared to digest the truth?
While importance of feedback from the employee is laudable, has your top leadership did some management audit? If yes, on what parameters it was done? If you do this audit, then there is no need to ask employees anything because the shortcomings in the organisation will be well visible to you!
Conducting ESS requires organisational maturity. Has your organisation acquired that maturity? ESS has to be done under the guidance of some senior. Therefore, is your management prepared to hire external consultant?
There are so many questions associated with your post. Please clarify and solution will be provided thereafter.