How to change light bulb

Looking  for a wee bit of assistance from you nice people...! My 2010 Lancashire has 2 round ceiling lights in the toilet/shower room, they have a small black on/off rocker switch at the side - see photo...

https://drive.google.com/file/d/1Wel6woPSqW9xLkEtLxpkr7ze9e8EEBea/view?usp=drive_link

One of the bulbs has failed but I cannot see how to get into the lamp - it won't rotate or unscrew so I think the plastic cover may just prise off, however I'm loathe to do so in case I'm wrong! I'm guessing this is the same light unit that's fitted to Nuevo's around 2010 so perhaps someone can advise how to gain access to the bulb?

Thank you in anticipation!

Gently prise it off with small screwdriver

No screwdriver needed. The diffuser has three clips that engage with the chromed surround. They are equally spaced and one should be diametrically opposite the switch. Simply flex the diffuser inwards slightly and it will pop out. Once one is out the other 2 are easy. It's a fluorescent tube. Check by swapping it with one of the others before buying a replacement. One of mine failed after just a year and it was the electronics and not the tube. Those Lights are no longer available and the best cure is to remove the electronics and replace with some small LEDs.

Thanks for replies guys, just need to locate a suitable bulb or LED conversion now... 

The fluorescent tubes are still available,  just the complete lamp is not. I replaced a tube earlier this year

O'Leary have stock of 9w PL versions and Jacksons are showing stock of the LED equivalents. The lights are called LUMO Crown I replaced a couple of them last year