Cook : http://www.cookfood.net/
Ready meals (that taste homemade) frozen and delivered to your door, there is actually a branch in maida vale you can buy from and they also do tasty kiddy meals.
Basilico : http://www.basilico.co.uk/
Really delicious pizzas freshly made. Located on Crawford Street so delivered very quickly. Lots of interesting choices and toppings. My husband recommends the Roma!
Tommi's on Marylebone High Street and Burger Shack on York Street (Royal Oak pub) both do fab burgers.
Afternoon Tea at 108 Marylebone Lane
We have had some lovely afternoons there. They are very friendly and often quiet at the weekends in the Pantry/lounge area. They also do amazing cakes and a great offer on a hot drink and slice of cake if you don't want to go for a full afternoon tea.
Two new branches of the Costa and Eat chains have opened on the southern end of Baker Street, opposite the Little Waitrose and near Portman Square.
Both shops are very larges and bright with lots of space for prams/children. They are also not particularly busy compared to the coffee shops further up Baker St. The staff are really friendly at both, and very accommodating to children. The Costa in particular has loads of high chairs!