If you bring along some fruit, crackers, bread and maybe a little charcuterie, you could make a lovely gourmet lunch by visiting The Farm House cheese shop which is attached to their factory just outside Agassiz. If I am ever in the area for any reason I stop in there - everything is outstanding, handmade from their own milks, and much cheaper than buying it at Les Amis du Fromage & other such places that stock the Farm House products.
is that pizza place still out there - or did it sell to new owner/operator? is it this one? - http://www.ah-beetz.ca/
there was a thread about pizza on Vanc board
i like the people at Leeps Farm Market - tho it is quite out of the way (east) of the Hwy 1 --- it is near the road that comes off the bridge from Mission - if that is on your route.
and this thread http://chowhound.chow.com/topics/792326
check out the blog mentioned - it appears to a be a british person living (or stuck!) in kamloops - interesting to read