Best way to tacke this?

The wife has had me build a seating area over lockdown out of 7.3 dense concrete blocks. She wants it finished in render. This is where my naivety kicks in, who knew rendering is a science. So here goes "help".
1. Should I go for S&C or OCR?
2. If S&C what ratio? Fibres, mesh required?
3. Do I have to prepare the surace, if so what?
Thanks in advance.More questions may follow.
Cheers