Yes the family hubs were the main ones I took our little one to, king farm & riverside stay & play. Unfortunately not as many classes now. Also if you go into Gravesend town they have one down by the prom. Noahs Ark is another one in the church hall next to the pocahontas statue on Mondays & Thursdays Peas & pods up near the lion garage on Wednesdays Think they are all shut for half term at the moment. Believe they all have a Facebook page if you search for them.
We used to go the cloud baby sensory classes at cyclopark, lovely friendly bunch and was gutted when my daughter grew out of it and "graduated" x
There’s the Family Hub they do lots of different play groups throughout Gravsend/northfleet you can look at there time table online xx