payment and invoicing process

Hi!

I might be in the wrong part of the forum and I kindly ask to move me to wherever is the correct part of the forums for my question.

Here’s my issue:

I have a courses page. I want to offer 4 different classes every 3 months. So it’s not going to be crazy busy at all. I installed woocommerce, but it’s way too complicated for me. I’m going grey over this and I don’t want to use woocommerce anymore. So the courses page has 2 top products (the bottom 2 are what I’m going grey over in woocommerce).
I want people to click on the buy button, then they enter their details for an invoice (one for them and one for me or else the finance agency in my country is going to kill me sort-of-thing) and then they pay.

so it’s select, click on buy now, enter details, receive invoice, the end.

I don’t want any individual accounts set up for people with logging on problems and so on, or anything like it. Shopify lite is not an option as I’m going to drown in fees and I haven’t been able to grasp Opencart either ??

is there a way to accomplish this on the cheap and as simple as humanly possible? I am starting my business from financial scratch and I need to start somewhere before I can hire someone to fix this for me.
aren’t there 2 plugins that do that and that work together really well?

I’m desperate and really appreciate any help at all!
Thank you loads in advance,
Martin

The page I need help with: [log in to see the link]