A little closer to home (for us at least) is Hampstead Hill Garden & Pergola. Just west of the heath, the Pergola, commissioned in 1904, is a gorgeously historic place to get lost in the middle of the city. Although the building is a little run down, you can still appreciate the architecture and gorgeous garden that surrounds it.
Close by is the Bull & Bush, a very cosy, traditional pub with a menu of tasty gourmet pub grub. Serving a fine dining-style roast on Sundays and everything from Asian Duck Salad to Margherita Pizza too. Their beer garden is on a main road, but it does get the sun until early evening.
For something a bit more adventurous, we love DIEP, a Thai takeaway with a massive menu of curries, noodles, wok dishes, street food and more, with vegetarian, vegan and gluten free options!
One of our brunch/light lunch faves in the area Les Filles Kitchen have recently moved out of Hampstead, but you can visit the in Paddington or Lancaster Gate if you're near. They also do home deliveries in London, just call them the day before to place your order!