Well it's not a timeline but there's Rich Rostrom's suggested
point of divergence where von Moltke's representative Oberstleutnant Richard Hentsch accidentally stumbles into a British cavalry patrol whilst on the way from 2nd Army HQ to 1st Army HQ on the 9th September 1914 and is captured, von Kluck therefore not being informed of Bulow's agreement with Hentsch to withdraw his Army north and opening a gap between them. The Allies push forward as hard as possible and over the next several days 1st Army is effectively destroyed with 60,000 prisoners being taken. The Anglo-French attempt to turn the German right on several occasions but are blocked by their reserves who in turn try to counterattack and return the favour in a kind of reverse Race to the Sea with the front lines eventually settling down roughly 50-70 km east of our timeline's, thus seeing western Flanders and much more French territory remaining unoccupied. From there further changes occur.
Alternatively there's Deckhand's
Rouleau Compresseur timeline where General Georgi Skalon the Governor-General of Warsaw and Commander-in-Chief of the Warsaw Military District is assassinated by a Polish nationalist on 12th March 1913. His deputy one General Aleksei Brusilov, who in our timeline transferred to the Kiev Military District at around this point in our timeline due to poor relations with Skalon and the toxic atmosphere he fostered, steps into the breech to secure the situation and is later confirmed as Commander-in-Chief. Brusilov continues the combat training reforms he carried out in our timeline, takes the opportunity to clean house and knock some heads together to make sure that commanders
will cooperate with each other or be transferred out, and experiment with some new cavalry tactics he was considering which develop into a kind of proto-deep battle theory. The Germans have a much harder time on the Eastern Front being beaten back, a large part of XVII Corps is forced to surrender with the other troops either withdrawing to Koenigsberg which is invested or retreating behind the Vistula as planned in our timeline if things went wrong. This in turn causes knock-on effects elsewhere.
Other ideas include the always popular amphibious landing at Alexandretta, modern day Iskenderun, rather than at Gallipoli to cut the single railway line that was the logistical lifeline for the Ottoman forces in Palestine and Gaza that ran nearby. With their supplies cut a large well-equipped British push up from the Sinai and a parallel one along the Euphrates in Mesopotamia could potentially see a large part of the Ottoman forces captured, or at least force them to retreat to the Anatolian plateau which is ideal defensive territory. At that point the British, with a few token French units IIRC, would hold most of the Middle East with the Ottomans limited to territory roughly equivalent to the modern Turkish Republic. They might not want to negotiate to begin with but if things are going poorly for the other Central Powers they might decide better to write off the rest of the Empire and at least bow out with a mild peace keeping the ethnically Turkish areas.
IIRC most of the faults with the Grand Fleet were either known about before the war, the faulty shells or not very large amounts of gunnery practice time available for certain units, or could possibly be averted if a key person or two were appointed to other posts or fell down a flight of stairs and broke a leg at certain points during the war. I'm not one of the
Battleship Brothers though so I'll leave that area to others.