Combining versus separte installations?

I have two sites, one starting with blog. and the main one without. I've moved the main one into GeneratePress. Since the other one needs a different header, sidebar, plugins, etc., it seems easier to me to have two installations. My web site host thinks that's a nuisance to keep updating and I should combine. But all the answers I see about a different header, etc., requires writing code. I DO NOT WRITE CODE. I can edit HTML but no way can I write code from scratch and it's not in my top 1,000 things to learn. Nor do I have money to pay for this. Anyway, I've managed to learn how to export, customize, etc. and I want everything on the site to be done by me so I know how to fix/change for future.

So is there a way to have my blog and main site within one installation, given that I won't be writing code?