On average, how aware of the political events of the era would a working class individual within the UK and its colonial possessions (including the American colonies) have been during the first half of the 18th century?

With the minor caveat that the 'working class' is a 19th century Marxist construct predicated on industrialised labour practices, the experience of urban workers in the early 18th century would have been a politically engaged and active one.

I can't speak to the American context as that's somewhat beyond my expertise (although I suspect that many of the points I'm about to make would map onto the urban American context, particularly given the high literacy rates in 18th century New England). But in Britain at this time, there was a high level of cross-class political engagement, for two reasons: the development of the newspaper, and the popularity of the coffee house.

Both of these innovations can be grouped together under the heading of 'the public sphere'. This category was developed by the German theorist Juergen Habermas in 'The Structural Transformation of the Public Sphere' (1962). Though it's been extensively critiqued since its publication, the essential theory is sound: that Europe in the late 17th and early 18th century moved away from a 'representational' culture (i.e. court culture) to a 'public' culture in which bourgeois individuals came together for the purposes of political and cultural discussion; thus forming public opinion as a valid political force.

So looking at early 18th century London - and, to an increasing extent, important regional capitals such as York and Edinburgh - we have a time and a place where cultural and economic conditions make 'working class' political engagement possible. Newspapers are flourishing, and promote specific political viewpoints: while Addison and Steele's 'The Spectator' skews Whig, Swift's 'The Examiner' is decidedly Tory. While the sales of these papers were modest, their actual readership was much, much wider because most readers picked up the paper in the coffee house or tavern they frequented. Literacy levels were high - in 1720, 66% of London women were literate, compared to around 35% of women across England as a whole, and the rate for London men was even higher; certainly over 80%. (This figure is based on the problematic measure of whether an individual could sign their name, but it's the best indicator we have). London's apprentices and artisans needed literacy in order to run their businesses; and thus could access the news of the day. And for those who couldn't read, cheap woodcut prints and political ballads (which were sung in the street by ballad-sellers) provided more information.

Something else to consider, in the London context, is that political events are literally happening in the street beyond one's door. The 1710s were a turbulent decade, thanks in large part to the succession of George I (the first Hanoverian king) after the death of Anne in 1714. The numerous riots that broke out between 1710-14, in London and in other towns and cities across England, were a conservative reaction against this new regime, against the Whigs (who supported the succession), and against Protestant Dissenters (ditto). Apprentices were reported to have been the main instigators of most of these riots, demonstrating that workers were not only aware of political events, but deeply engaged in them.