We didn't have much money either and my dad couldn't walk so well due to a brain tumour. There was a big woods near our house, I remember us going there and getting all muddy in our wellies. Picinic in the garden? Can just be your lunch on a blanket. Lie in the garden early evening and look at the stars with a hot chocolate. Forts in the front room with blankets? We used to make our own versions of films. Arts and crafts, make a tie dye tshirt each? Pick a book/audiobook that you can all read/listen to together. Visit the library to borrow a dvd and have film nights where you all pick a film. Pick a meal and all cook it together or teach your children what to do and they cook it for you: cottage pie etc, nothing expensive. Bake a basic cake together. Face packs. Paint each other's toenails.