Up on the common, the Amberley Inn is really lovely (how old are the DCs? might be better suited to older ones) or the Black Horse at Amberley.
As someone mentioned above, the Lavender Bakehouse has vair nice cakes as well as tasty lunches. Child friendly but right on the main road and very limited parking.
If you're here over the weekend, the Stroud Brewery does pizzas on Friday and Saturday evenings - very relaxed and low key, they start serving at 5pm and you want to order as soon as you arrive. Brilliant for the kids, plenty of toys to play with, even a dressing up box! They do free teas and coffees, hot waterbottles and blankets too for the undercover outdoor seating area!
Also on the weekend, you'll need to see Stroud farmers' market, really lovely.
For your knick-nacks, hop over the valley to Tetbury, for some really brilliant antique/ brickabrack shops, such as "Top Banana". Nailsworth is similar but not quite so many shops there, although they do have the FAB toyshop in the old bank "Enchanted Childhood" and "The Canteen" which is nice for a relaxed lunch. Check out their home made marshmallows on sticks!
Look out for the Winstones Icecream parlour up on the common, a stone's throw from where you'll be staying.
Sorry, I've not provided links, but everything will be on google.
Have a lovely stay and wave as you go past! 