I am quite an advanced user of K2, but this simple thing seems to have confounded me today. I've searched but no luck so far.

What I want is to show a K2 category as usual from a menu item. However, I want the items to open in a different menu item (as I wish to display different modules).

I do not want to make item specific menu items, as this is a blog. So I need an alternative category page, that the user is directed to after clicking "read more" from the original category page.

Cheers for any help!

I do not think this can be done. The items will always be rendered from that category.

Alternatively you can display items from other categories using a K2 Content module.

Thanks for this.

Yes I think a content module might be the best idea for the 'category view' and then the item opens on the real category page which is a different menu item.

Another idea I had was to build a template overide with module positions included in it, but it was quite complicated to get all the module to show properly.

I am afraid this is the only solution. You need a template that has template positions above the component area.