Jeremy Warner argues
that the difference between British and Spanish austerity is that Britain is aided by devaluation. Setting aside the issue over whether that would really be helpful, the truth, as the chart below over the change in the pound's value, is that the pound has been revalued
(with an "r")* significantly against the Spanish currency during the latest year while it is Spain has seen its currency significantly devalued.
So granting for the sake of the argument the view that a weak currency makes austerity more feasible, Spain is in a better position than Britain, not the other way around.
*=or more technically appreciated, but never mind that now.