I have a "Glow Worm" combi boiler that has been losing pressure slowly - from 1.0 bar to 0.6 bar over the course of a few months.
The instructions simply say that to restore pressure, "slowly open the filling tap beneath the boiler to pressurise system to 1.0 bar. Ensure filling tap is then closed."
Being utterly hopeless with all things home-maintenance-related, I hope Stack Exchange can offer some advice! The underside of my boiler looks like this:

The only thing that looks like it might be a "filling tap" is the blue blob in the middle near the top of the image. Close-up:

As far as I can tell, the blue bit on the end doesn't twist or pull off to reveal anything underneath - though as the instructions say "slowly" I haven't twisted very hard. The shiny band just above it turns with no resistance at all, and I don't think turning it is doing anything useful.
Can you offer any advice as to where I am going wrong? Is restoring pressure just a matter of turning the tap (when I find/manage it) on and off again?