Remove cart + product pages in Woocommerce

Dear,

I would like simplify / speed up our shopping process. We only have 2 products. Ideally:
1. click on product (which can be found on normal page)
2. go to payment page
So no cart, no separate product pages and no shop page.

I read about 2 options:
– to ad (redirect-) codes to functions.php (and change add to cart text) –> I can not find where to do that + I am no expert, what are the risks of doing this myself?
– buy the Woocommerce extension: One Page Checkout. Would you recommend that extension?
I do prefer to try free options first.

Thanks!