Automate report generation on a website without opening the browser

I've been looking for a solution to that problem for a while but couldn't find anything satisfying.

Basically, people from my team have to spend a few solid hours everyday on filling up some web forms to generate pdf/excel reports. The whole process is actually a couple of html form fills and button clicks based on the data manually obtained from some other system. We need to specify some parameters (report date, type and few others), click the "regenerate" button and once the process is done (new page saying "Report successfully generated") go back, select the report once again and click "Send to your mailbox".

Are there any tools/packages (preferably in python) I could use to write a script that would do it without opening the browser? Let's say, give a list of parameters (excel spreadsheet/csv) for every report that we want and loop through it to perform these tasks in the background without user interaction.