Power Cable DIY - Please advise

Technically speaking, there is nothing to stop you from wiring in some normal GTX receptacles and FI-28 male plugs to a UK 220V circuit. It should handle it just fine (it’s just a metal conductor), as long as you stay within the equivalent amperage (at 220V, you wouldn’t want more than a 10 amp circuit). Where you would get into trouble is that you would probably be doing this against local UK wiring codes. I don’t know the UK standards, but this could affect things like insurance claims if somehow this outlet caused a fire. Even though you know it’s a 220V circuit, there’s always the risk of some idiot plugging in a standard 125V device and causing that device to fry itself and possibly cause a fire or more.

Even the US has strict codes on what kind of outlets are placed. You can refer to this chart to see.

http://www.digikey.com/en/pdf/q/qualtek/nema-chart-non-locking-plugs-receptacles

When looking at normal 15 amp circuits, you can choose a 5-15 outlet or a 5-20 outlet. The 5-20 outlet has a special blade insert which allows both 5-15 and 5-20 plugs to be used. However, that 5-20 plug cannot be inserted into a 5-15 outlet (this is mainly a safety measure from the wiring code to prevent over-extending a particular 15 amp circuit and causing electrical fires/problems).

There is also a special 220V outlet in the US called 6-20. You need a special industrial plug for this and it’s really not used for electronics unless you want to use something like a brass Hubbel 220V plug. Again, the reason for this special blade configuration is to prevent someone from plugging in a normal 125V device.

As far as the outlets, if you want to do the wiring yourself and understand that it’s a 220V circuit, feel free to use a GTX on this.  Just make sure your electronic equipment is setup to accept 220 volts.  Once again, I don’t know your local UK codes and what is acceptable and what’s not. This would violate any wiring codes in the US for sure.

http://www.vhaudio.com/acreceptacles.html

VH Audio here in the USA also sells UK and Schuko outlets and plugs, if your interested. I’m sure there’s a UK source for Furutech plugs.

As far as IEC inlets are concerned, I have used the Furutech IEC inlets successfully.  I have both fused and non-fused inlets.  They are a good addition to your equipment.  VH Audio sells them as well.  I'm sure you can find them somewhere in the UK.

http://www.vhaudio.com/connectors-ac.html#IECinlets

Just make sure the dimensions of the inlet and the mounting holes line up exactly.  In my opinion, the IEC inlet upgrade gives you a subtle improvement in sound, but it's not as large of an upgrade as a excellent power cord.