firstly yes that looks like a pet flea. secondly what spot on treatment did you use? thirdly you can buy a product called Indorex in a spray can and spray your house to treat the unwanted fleas until your cats flea treament starts to work. but it's best to use this in conjunction with washing all your loose linen and clothes and vacuuming the house. We sell it at the vets but i'm sure you can get it elsewhere. have a look online. be sure its what's on the tin though as another product might not work as well. as for spot on treatment for your puss...

Frontline combo(combo for top market meds not just 'spot on' which is a different dose and meds may not work as well)doesn't cover mites and only some worms)
Stronghold(covers fleas, mites, ticks and some worms)
Advocate(fleas, ticks, mites and some worms)

also if there are fleas there are usually worms from ingestion of the fleas best to get some Drontal or Milbemax for worming. be wary and don't depend on ones you get from the Tescos(etc..) or some pet shops (ie. bob martin)