In principle, yes. There are human rights in issue and Hamish Birchall has looked into it. In my view the government has the right to make restrictions (on human rights) that are necessary in a democratic society - but that restrictions on acoustic music are not "necessary" for that purpose in that social evils (noise, disturbance, safety hazard, moral hazard) are not sufficiently likely to arise therout for 100% licensing to be justified.
The government says it does not accept that even acoustic music is never noisy.
Others say that there are other measures to control noise from electric music so that too ought not to need 100% licensing (I violently disagree, since I live between two pubs, and suffer their music for my sins).
But I imagine (injunctive relief under EU law is not my expertise) that until there is a law made by Westminster which fails the test of necessity in a democratic society, there may not be a cause of action under these principles. If so we would have to wait until the law was passed and then take the government to court. I have tried that before on a very different issue. Be careful. They play very hard ball.