As it states on the unit 'constant voltage' it should be possible to replace it with any constant-voltage 24V power supply unit rated for at least 8.4W or 0.35A. It does not have to be specifically an LED driver.
Other than from the original manufacturer, you probably won't get one with the same 24V output socket. You might have put a barrel jack socket onto the captive output lead of the new PSU, or cut the plug off the lamp cable and splice together. Beware those clear leads don't always have separate insulation for the two cores because they are designed to be moulded into the plugs.
FWIW plugs and plug-in power supplies should not be sold in the UK without either UK plug pins or a permanently attached UK converter. A separate 'travel adaptor' is not acceptable although a lot of sellers seem to think it is.