The only two people I know for a fact have ordered through ENCS are myself and MACF. This is what I can tell you about the process to help you out. You will pretty much pay the same amount of money for it as someone in the States would who orders a 'built to order' Raptor at a dealership. Your base price for the Raptor will be lower, but with shipping charges, it will even out pretty much.
Your order will go to the front of the build queue for the manufacturer, but that's true with any vehicle ordered through ENCS. From build day to delivery (in the UK) it takes about 2 months, give or take a few weeks. I have done this process twice. In 2009, I ordered a Dodge Charger and within a few weeks I had a factory build date of 15 October 2009 and I was driving it on 8 December 2009.
My Raptor is a little bit of a different story, because I wanted it supercharged and didn't trust any British speed shops to do it because it's HIGHLY unlikely any of them have ever even seen a Raptor or know what one is, so I had it sent to JDM Engineering in New Jersey right from the factory. The way this changed my order is I had to take Stateside delivery and would have to work out the shipping on my own. When I ordered my truck, ENCS shipping would have been $1200. I called a few places in the states to get quotes for shipping the Raptor from New Jersey to the UK and they were all in the $1500 range. My order officially went in to ENCS in early September. This was a little frustrating because the order banks in the States seemed to have opened like a month earlier than that, but ENCS didn't recieve the specs in their order bank until then (early September). Regardless, the truck went in the queue and I had a build date within two weeks, which was going to be 15 October. The truck arrived at the Ford dealership in New Jersey for JDM to pick up on 2 November, and it probably would have gotten there sooner except for all the havoc caused by Hurricane Sandy at the time. JDM had it in their bay by 9 November. They were finished with it by mid-December, but it had missed the December boat cutoff time by a few days. It did make the early-January boat and it's actually scheduled to come into country today, but since it's a weekend, it won't be offloaded until Monday, so I can't pick it up until Tuesday. The paperwork process for shipping it yourself is a bitch and a half. I highly recommend letting ENCS do all this for you unless you have a situation like me with wanting the engine work done before you get it in a foreign country. Hope that helps. If you have any questions, let me know.