Here is the thread I started when I was looking for a simple recipe:
I haven't brewed it yet, but I'm going to try this one from that thread (posted by TimTrone):
8lb marris otter
1lb brown malt
4oz pale chocolate
"Use about 25 IBUs of a English or English type hop. Willamette, Golding, target etc. the hops aren't so important in a beer like this. It's more malt focused."
I would guess you could stock up on the MO and either Brown or Crystal Malt, and get some crystal or brown, chocolate, and biscuit malts (seen that in other recipes) when you want them. I think a northern brown might have higher IBU requirements.
I am by no means an expert, but hopefully this helps!