Hi @paul_wareham,
It will be very easy to generate the SendGrid attachment content with the CSV node. The content will be stored on the payload, and you will then be able to include it as an attachment to SendGrid in an HTTP Node.
I built an example, but used a Virtual Button with a CSV formatted string.
Then I make it Base64 friendly:
Then I use an HTTP Post to SendGrid:
Then my payload will reflect this request, and an email comes through with my CSV attached.
Hopefully this helps!
Julia