One of the main reasons why people watch comedy, and often TV in general, is that they can relate to the characters. This could be in themselves, or through recognition of others'.
For example, the target audience for Bad Education is teenagers and young adults, and because the characters are these ages they are relatable. Alfie, the main character usually has good intention but always manages to make bad situations worse. This trait can usually be seen in at least one person from a group or colleagues, but is still entertaining when dramatized on screen. Building on this element, the characters are consistent in their personalities which works to create a sense of anticipation as they are put in each scenario. Familiarity within content and setting is a sort of comfort to audiences, as they know what to expect so can enjoy the jokes without having to think about the story line- one of the attraction of comedy as opposed to a drama series. Another benefit of familiarity is that the audience have an opportunity to build up a sort of personal relationship with the characters- particularly the ones they can self-project onto.
In regards to plot, many TV comedies such as Bad Education and Miranda offer snowballing narratives. This is when the situation gets worse and worse- usually due the main character- specifically Alfie and Miranda. Although in theory this technique sounds of it could get boring throughout a series, it allows for spontaneity in the direction of the plot.
On top of this, there is usually a running joke throughout the episode which is incorporated into the scenes. These elements are attractive because they add a sense of surrealism, which adds interest to the on-screen lives of familiar personas. Eventually, however, narrative resolution becomes more appealing because it gives the audience a sense of security in that no matter how bad or ridiculous things get, the events will always be 'resolved' to some degree in the end.
