I have a book recommendation:

I have recently read and enjoyed The Sleepwalkers: How Europe Went To War In 1914, by Christopher Clark - it is an informative and comprehensive account of the actions of the people who took Europe to war: the foreign ministers, ambassadors, heads of state and various nationalistic elements of all the countires involved. While it doesn't focus very heavily on Britain, but rather tries to give an account of all the major players, it is very detailed.

Tuchman's thesis is sometimes referred to as "war by timetable." In essence, she posits that the mechanisms of mobilization could not be easily halted and that once a preliminary decision to go to war was made it could not be reversed. For each belligerent, the risks of postponing or canceling mobilization in the face of mobilization by their adversaries risked losing the war entirely. So the pressures to mobilize, to fulfill the "timetable," overrode other considerations that might have militated against going to war.

This view has been challenged by many historians, including Clark, author of The Sleepwalkers, as mentioned below, as well as Keegan (The First World War) and Gilbert (The First World War: A Complete History).

The major theme of Sleepwalkers (ircc), which is one of the more major works published recently, is that the war had many, many causes. This itself isn't particularly notable as many authors have argued that blame for the war was scattered among the belligerents and not solely the fault of one nation. What is important about the Sleepwalkers is the arguments that it makes about the centers of power within nations and how these centers of power, or rather centers of policy, were often competing. For example, Clark writes about the competing interests of the military and the foreign service in Serbia prior to the war. On the one hand, the Serbian military supported "irredentist" forces in Bosnia (i.e. the "Black Hand") as well as other parts of the Balkans, while on the other hand, the foreign service sought to mollify Austria-Hungary and tamp down down on Pan-Serbism if only to avoid drawing the ire of Austria-Hungary. In other words, Clark posits that while much of the historiography has painted a picture of each nation having a sort of monolithic center of power, this was almost never the case. Inter-nation diplomacy was complicated by an inability to correctly assess the policy positions and willingness to go to or avoid war of individual nations. The result was a sort of confused milieu of different actors representing different positions among different states that ultimately allowed a full-scale war to break out.

edit:

You really can't go wrong with Gilbert's magisterial The First World War: A Complete History.

I'd also recommend Robert K. Massie's Dreadnought, the focus of which is the naval rivalry between Britain and Germany.

Gary Sheffield's Forgotten Victory is a fairly solid summation of one line of recent historiography focusing on the need for Britain to wage the war (i.e. it was not "futile" as Keegan writes) and the evolution of British arms during the war itself.

Lastly, just as a counterpoint, I'd suggest a look at Niall Ferguson's Pity of War. This work has received a fair bit of both criticism and praise and its thesis stands in contrast to a lot of what many historians have concluded. It's not what I would necessarily call "good history," but it is one of those focal points around which some of the modern historiography swirls.