Leaking stopcock

[spirit20]

I've a leak in my stopcock (picture below). The stopcock was just replaced in July, so I'm a bit annoyed it's leaking again. Would any DIY experts know if this is likely to be something I can easily fix, or if it's something I need to call a plumber for?

From what I can see, the waker seems to be leaking from the gland, and youtube videos seem to suggest this is an easy fix by just tightening it, but I'm worried of something going wrong..

Panicing a little over this as I'm due to head off on holidays next week, but obviously won't be able to if I've a leak. Any advice greatly received!!

Do you know where your external stopcock is? Turn off the water to your house before attempting it.

This is almost nothing, and many of this type of valve do the same. It won't suddenly flood out, just a little drip past the stem. Just need to nip up the top nut a little, but not too tight.

No actually, I better find this out.

Thank you! I'll do this as soon as I figure out where the external stopcock is.