Flamazine will be given as a prescription. Until you can find a vet to prescribe some (I'm not sure about directories of herp vets for the UK) you can use the neosporin (WITHOUT pain reliever) that Lija suggested.

You really also need to figure out what has stressed your frog out to cause such a terrible nose rub. If you check out the "trouble in the enclosure" thread stickied in the tree frog section, and fill that out, along with posting pics of the frog and the enclosure, we may be able to help you figure it out.