Like uber, this is one of those styles that I can easily drink by the imperial gallon. Agree with much of what is stated here, but a couple things, don't hesitate to toss some torrified or flaked wheat into your grist and carb it low, like 1.8 - 2.0 volumes. The wheat gives it just enough stable foam to give it a nice creamy layer all the way to the end of the pint, at those low carbonation levels.
Light invert sugar is pretty much 100% fermentable, but not so with invert 2, 3, or 4. Adding a pound of invert 2 or 3 can make an incredible impact on a bitter, without drying it out too much. Lots of dark fruits, toffee, cherry flavors can come out with these darker sugars. Not sure I'd go with something as dark as a 4, but I'd highly recommend playing with some of these sugars.
For hops, agree with fuggle, but there's the classic EKG for which you can't go wrong. Bramling cross and Northdown are also nice. It's a good opportunity to try out some of those UK hops that you might not try otherwise.