No, that's not right mate. Currently, registration in the UK doesn't make you compliant in any country except the UK.
All this will change from July 1st when the new EASA (EU and UK wide) rules come into force, and all drones with a camera will need to be registered regardless of weight.
But the question is will you be able to submit an application to register and have it be approved so that on July 1, you will be in compliance? Seems like there's very little explicit acknowledgement by individual EU country agencies that they're working towards compliance and enabling registration which would be in compliance.
As far as the UK, would they even bother trying to produce a compliant regime with the knowledge that in 6 months, they may no longer have regulatory alignment with the EU?