I mentioned this to Huw at Tekcel, this morning. He gave me a little more information on this.
Milling tends to be used for engineering works, turning metal etc. They often start with a block of material, normally metal and mill this into a solid shape. Due to working with metal and the heat involved they tend to flood the material with a coolant. I would expect companies like Rolls Royce to have quite a few.
A CNC routing machine is more likely to be relevant to you by the sounds of it. For fret cutting and producing rim and return letters, you are likely to be using soft materials so little need for coolants, but compressed air or atomising oils are available for metalwork.
CNC Routers require a good vacuum to hold the sheet material in place.
A good CNC router will need little or no secondary processing of the finished edge.
If you did want more advice, I would certainly suggest speaking to Huw (01275 342 668) and visiting their website www.tekcelcnc.com