How to create a program which makes, shares, approves, and saves forms?

Question

Hello all,
So far I am just learning the basics of python, Js, HTML + CSS.

So I want to digitalize our form handling at work.

Currently approval forms must be filled out, sent to the approval person, sent back to original sender, and stored. This is all via paper and fax.
I want to be able to do this digitally. I sort of have an idea on how to code, but I'm confused what platform to run it on?

At work we have to go through "cloud risk assessments" before any new program is able to be used. and as far as websites go, we can only use or social intranet (which we can't put code in) or SharePoint (which modern is difficult to put stuff in)

With this taken into consideration, where do I start? Can I finish a project like this within six months? How long should I tell my boss it would take if I mention it? (This would be a side project, I do not actually have a job as a cider)

Thanks