You can probably profit from repeating fields, but I guess we need to know more about the real dimensions of the matrix you're trying to render and about the real data you need to represent.
The Months will be a continuous set, so 12 per year but the data will continue to grow, hence I was planning to create a table with fields:
1. Month Name
2. Field 1
3. Field 2 etc.
If I created the data in the spreadsheet equivalent, I'd need a field for each month, and the number of fields would grow with time which is not good design I believe.
I could probably create the layout with say 12 months displayed, where the user sets the start and end month.
Could you please elaborate on what you mean by repeating fields?