Only 8-10 kms from Central London and easily accessible on a multitude of trains, tubes, buses (use City Mapper for your easiest route) Hamstead Heath is the countryside in the middle of a very busy city. You can take a stroll up Parliament Hill to see views of London and the bright city lights.
Its a hot spot for local dog walkers so a great place to get your doggo fix walking through the gardens and woodlands.
Kenmore House at the top end has a lovely outdoor seating area for a cosy coffee on the terrace.
And if you’re feeling brave / a little crazy you can even take a dip in the swimming ponds, separate swimming areas for ladies, men, communal pools and a no phones allowed zone so you can really switch off and enjoy a book by the water. Or alternatively find a cosy pub in Highgate and get toasty by the fire.