This tendency is evident in the occasional Scottish example as well. The soft, roasted character is usually from chocolate malt. Other English stouts occupy a middle ground between the sweet and dry styles, and much variation in palate and balance occurs between brewers. Some English stouts are quite intense. Cream stout is reasonably descriptive of the palate of English-style stouts.
Oats are even harder to work with than flaked barley or wheat malt.
Use the most heavily processed oats you can get. Instant-type oats are much more thoroughly gelatinized than regular oatmeal and are used by some commercial brewers. Avoid steel-cut oats unless you are prepared to cook them before mashing. In both cases I recommend using an iodine test for conversion, although the results can be hard to read in a stout mash. The delightful texture of oatmeal stout is best expressed in the unfiltered form, which is just as well because filtration is usually very difficult.