Anything with Jane Horrocks in it has to be a treat. Have watched her career since I first saw her in "Life is Sweet". Then she turned up as Bubble in "Absolutely Fabulous" and was great in "Little Voice" Recently was in an episode of "Jericho". Always different and always wonderful. Nice seeing Stephen MacIntosh again too.
What type of accent does her character have (and I assume it is also Ms. Horrocks' own accent, because her characters all seem to have it)? What area of England is it from? Does it imply a certain social status or level of education?
Actually, it's a Yorkshire (West Yorkshire) accent -- they live in West Yorkshire.
It's a standard Yorkie accent, not necessarily indicative of class or education, unless it's really thick .... But of course it seems slightly out of place with the posh London MPs and members of the House of Lords and the Conservative party old-timers.
A classically trained actress, Horrocks doesn't use her birth accent in the series. Nor does she use it in other things she's in.
All of the Eatanswill characters (except the actor who plays her husband, who just uses his normal accent) on this show speak with a distinct Yorkie accent, including the actors (which is most of them) who weren't born and raised in Yorkshire.