I'd avoid the Bristol Brabazon idea.
Hopefully, that means the Britannia is started in 1944 instead of 1947, which in turn may advance its first flight from 1952 to 1949 and its service entry from 1957 to 1954.
And while your at it I'd avoid the Saro Princess.
No Brabazon and Princess means the Proteus doesn't have the reverse-flow layout that Gunston (writing in The Encyclopaedia of Aero Engines) said caused the flame-extinction problem due to ice accretion that led to BOAC delaying it's acceptance of the type for two years. So could that put the Britannia's service entry forward to 1952? I'm sceptical because the engine didn't run until 1947 and AFAIK it had a lot of problems that weren't solved until after Hooker joined the firm in 1950. So I'm going to be cautious and say that it entered service with BOAC in 1954.
Gunston writing in Rolls Royce Aero Engines said that the Lord Hives made a big mistake by abandoning the Clyde turboprop. (It's safe to say that at the very least that the Wyvern would have been in service sooner.) He wrote that the only thing wrong with the Clyde (which first ran in August 1945) was the overloaded LP, but with 2 or 3 stages power & efficiency would have improved producing an engine in the 5,000hp class. He continued that this engine would have been outstanding for large civil transports and that it also had the swift fuel/propeller control that was essential for military aircraft, especially when flying from aircraft carriers. He concluded by writing that had the Clyde been put on Britannia in 1950 it would have been in service many years earlier and many more sold.
However, the Britannia's started in 1944 instead of 1947 ITTL the Clyde is selected for the aircraft in 1947 because it is well ahead of the Proteus in development and the aircraft enters service in 1952.
IOTL...
£6.45 million was spent on the Bristol Brabazon to February 1952
£9.10 million was spent on the Saunders Roe Princess to May 1954
£4.00 million was spent on the Vickers V.1000 to December 1955
I agree that the V.1000 should not have been cancelled (although that happened in 1955 and this thread is about the period 1944-54). What should be done with the money spent on the Brabazon and Princess?
One possibility is a more ambitious Brabazon Type I specification. That is make it a large turbojet powered aircraft for the North Atlantic route instead of a large turboprop powered aircraft for the North Atlantic route. As it will take time to develop the engines the Type I (Brabazon) and Type III (Britannia) are still started in the opposite order to OTL. The contract to develop the TTL version of Brabazon Type I is given to Vickers in the late 1940s so it effectively means the V.1000 (or an aircraft of similar capability) is started several years sooner and makes it's first flight around the same time as the Boeing 367-80. (That is, July 1954). One problem that I can see with that course of action is that Vickers might not have the design capacity to make an earlier start on the aircraft without delaying the Viking family, Viscount & Valiant which will be given priority so the first flight of the ALT-V.1000 may not be until 1956 and it's service entry around 1959-60. So the earlier start might not result in the V.1000 entering service with BOAC, TCA & the RAF any earlier.
Therefore, I think that the money & design resources saved on the Brabazon should be used to design military derivatives of the Britannia. So perhaps a LRMP version to be procured instead of the Neptune and compliment the Shackleton which ITTL might have Clyde tuboprops instead of Griffon piston engines. (As I've mentioned a LRMP version of the Britannia the licencing agreement with Canadair would be signed 3 years earlier so the Argus is likely to be in service 3 years sooner too and so will the CL-44 but the latter aircraft might have Clydes instead of Tynes.) Or develop an equivalent to the Britannic/Belfast that could be put into service in the middle of the 1950s.
Another possibility is that the resources not put into Brabazon and Princess are put into the two firms helicopter projects.
I also think that the rocket fighters were a dead end. Therefore, the the resources that were put into the Avro and Saro rocket fighters (including their engines) and the Princess flying boat might have been used more profitably to make an earlier start on ballistic missile research and a stand-off bomb for the V-bombers . This effectively means an earlier start on Blue Steel and Black Knight.