in general the supermarket stuff doesnt work, bob martins has the added extra of fits and possible death so deff a good decision to avoid that!
As theyre so young, id go to the vets as theyll need the kitten wormers in anycase and its not worth risking overdoses. im not sure whats used on kittens but Frontline is i think from 4months up ( 16 weeks)
If you cant treat the kittens, i would treat the house but use a proper product (the ones you can buy in supermarkets really dont work) from the vets or from somewhere like Vetuk.co.uk - R.I.P fleas is good, or idorex. theres some other i cant remember, theyre about 15 pound from the vets