When creating a spread page I would like to work with 12 text columns with 5 mm white space, however I want to keep 25 mm free in the middle of the spread, is there a faster way to set this up, without the manual guides?
You can control the gap between two pages in a spread via the inner margin value when you set up the document, or you can modify it at any point via Layout > Margins and Columns. So you can change yours to 12.5mm inner margin and it will apply that to the right edge of your left pages and left edge of your right pages.
If you don't see separate inner/outer margin values you need to change your document settings to facing pages.
If you have set up one page then you won't get inner and outer margins, just left and right. I would always set this up as two facing pages, even if it's only one spread, but of course you could always just set it up as two columns with a 25m gutter, then create two text frames and modify their settings to 6 columns with 5mm gutter.