In my opinion, something like Biscuit or Victory malt is unnecessary if you're starting with a flavorful Pale Ale malt as your base. I'm a big fan of Crisp Floor-Malted MO. I've also used malts from US craft maltsters that are really good in these styles (I'm using Ye Olde Pale Ale from Sugar Creek right now and enjoying it a lot).
I brew a lot of moderate gravity English ales in the 1.035-1.040 range, and the biggest factor to me is carbonation. I use invert sugar in a lot of my recipes, so they end up attenuating pretty well. It's easy for me to end up overcarbonating these, and they end up thin and watery. As a matter of fact, I just brewed a Brown Ale that had this exact problem. Once I blew off the excess carbonation the beer really came into its own.