Welcome to Social Slimmers!
Yes aim for at least 1/3 of your plate. Bol is usually made up of plenty of veg, even the tin tomatoes... tomatoes are super free.
Slimming worlds recipe: http://www.socialslimmers.com/slimmi...-spag-bol.html
Although pasta and potatoes are free I personally always ate them in moderation, I think some people can go overboard with the 'free' at first (a friend of mine did)!
Good luck on Slimming World