You've got the right idea, lots of base malt, marris otter will be nice, and some small additions of specialty malts. My personal preference is nothing too roasty on the specialty malts, I think my last BW was mainly crystal and some biscuit. If you're looking to use WLP002 there are a few things to keep in mind, one is that you need to make an enormous starter, as it's a low attenuating, highly flocculant strain, and second, it's an English ale yeast, so you're going to want to let it's malty notes shine with a less aggressive hop bill. Maybe some fuggles and some east kent goldings? I like my British BWs in the 30's range for IBUs. Happy Brewing!