Clive: there’s a calendar-making extension for LibreOffice Calc. Calc is capable of producing a very nice presentation that looks nothing like a spreadsheet.
A more powerful and amusing solution is to use the tikz environment of the document writing and typesetting system LaTeX. Tikz can be difficult, because to ensure impeccable results it’s deliberately restricted to using LaTeX functionality.
There were some beautiful calendar templates last time I looked more than a year ago, before the latest LaTeX calendar package was released (October 2017). There’s also one on a dodecahedron you can cut out and glue together. There are other solid figures to play with.
I use TexStudio as the front-end editor for LaTeX on my computers, but now often prefer the cloud service Overleaf. This gives you quite a lot of capacity for free, and it has most of the templates you can find on the web built-in. LaTeX works with a huge number of languages.
Overleaf may be the better choice for trying out tikz, because it always works. The maths functions of tikz sometimes fails on local computers that (so I read) have applications incorporating a (usually hidden) embedded LaTeX engine.