Done.
For me, what would appeal the most is somewhere the dcs (2yr DS particularly) can play and I can drink a coffee in peace, knowing that he can't run off/is in danger. So like a buzzer gate thing like they have at soft play.
Toy wise, I would avoid ball pool type things as kids can't seem to help throwing them :o
Farm is an excellent idea, train track, mini kitchen, duplo, colouring.
If you had an outside, then some scooters, ride on toys, a little rocking see saw or slide would be amazing.
Where we tend to go for lunch/tea and cake the most is a church run cafe, all food is made on the premises, meals are around £5 and you can get a mug of tea and a bun for less than £2. There is a separate room that they use for a youth centre that also has tables in and we sit there so that the kids can play but stay out of the way of others.
Hope any of this is useful :)