A few cruise missiles, or a few bomb runs, in retaliation would have been expected.
As you said, getting a dozen, or two dozens, of your citizens slaughtered and/or taken hostage would normally trigger a response.
Key word being normally.
Despite higher losses, the US hasn't done anything and the administration is, once again, out for lunch, while part of the media and the, almost, entire intelligentsia openly endorse and condone what Hamas did. At another period of time, Predator drones would have been flying circles above the area of operation of the terrorist groups, and rained down hellfire missiles until it's done.
The US hasn't done anything, and since they are one of the major sponsor, if not the main sponsor, of Israel, if the US hasn't done anything about it I don't expect the UK to do anything either.