Creating an Application - Creating and editing word, powerpoint and excel files through UI

I work at a law firm and we are currently doing a lot of standard repetitive tasks manually (like creating certain standard contracts for clients) and this is extremely ineffective. I would like to create an application which my fellow employees can use which allows themto automatically generate word files (primarily), but preferably also excel files and powerpoint files, based on their input.

I am imagining an application which is web-based. At first the employee will have the home screen, which then has several options like "create new contract", "Create new memorandum" or "Create new invoice". When the employee selects e.g. "create new contract" he will be able to fill in certain information in a UI about the client, and based on dropdown menu's also select e.g. what type of contract he wants to make, and what provisions should be included therein. Once he clicks "Create contract", the application will get the relevant information from a database which includes e.g. standard texts based on the preferences/input he selected. Furthermore, among others the client details should be inputted in the word file automatically, similar to the "mail merge" function in word.

Now the question is, what programming language(s) would be most optimal to make the above application? I have a hard time grasping which languages I need to make this.

As you can probably tell, I am currently a beginner in programming. I know a bit about HTML, CSS, JAVASCRIPT and am currently learning to work with frameworks like angular/react. Taken into account my beginner situation, would this change your answer to the above question? Which would be most easiest for me to learn? Note that I am very passionate about becoming a better programmer and am currently devoting all my free time at programming.

I have browsed the internet for and came across the following alternatives to create and edit word files. However, I do not know how the below relates to other languages required to make my application.

• Javascript library WebODF which is able to create word documents.
• Java API's (Apache POI or OpenOffice's Universal Network Objects Interface).
• Using Windows Powershell (however, no clue how I would connect this to a UI).

Thank you very much for your help!

Kind regards,

Jack