I don't quite understand what you're after here. Usually PCB designers use panel-mount parts (LEDs, switches, etc.) when they need to mount to a panel - like the name says. So these leads (what i think you're talking about when you say PSB header) are built into the part. If you're looking for what's called a PCB header - just straight pins for connecting plugs or another PCA, then check out samtec.com or molex.com; they make any type you need and probably have a distributor in the UK. Hope this helps, if not, please explain more.