Very near the site of the "Oldest Tunnel in the Oldest Underground in the World", in Rotherhithe in south east London, you can find the Brunel Museum, which, well, is not just 'a display' about his life and works, but an entire museum about his life and works.
The Brunel Museum is open every day 10:00 until 17:00.
Entry to the Brunel ...
The Wren Library of Trinity college is open to the public from noon to 2pm each weekday throughout the year and also from 10:30am to 12:30pm on Saturdays during university "full term". It's closed at Christmas and Easter.
Their website says, "There are six exhibition cases in which a small fraction of the Library’s treasures are on display" but it doesn't ...
In terms of a comprehensive museum, not yet.
However, if you are travelling in 2018 (or reading this reply in the future) then there will be a new museum called 'Being Brunel: the national Brunel project' opening in Bristol in a year's time.
The ss Great Britain Trust has today been awarded £4.78m by the
Heritage Lottery Fund (HLF) for Being Brunel: ...
I think your notes in the question pretty much cover it, but there's much more at Bletchley Park than just a display. There is:
In "Museum in Block B", a whole gallery titled The Life and Works of Alan Turing, including:
Copies of 15 of his 18 published mathematical papers. Here's a little about the story of how they were saved by an online campaign
@jl6's point in the comments is a good one, but deserves to be expanded upon (Brunel has been adopted as a local hero in Bristol). He's one of the few historical figures we've got who didn't directly get rich from the slave trade). See for example Isambard Kingdom Brunel, famous engineer and his work at Bristol (local tourism/history site) for a few more ...
You can see what items of the Science Museum's collection are on display, and in which museums, using their collection search. Putting in "Brunel" gets a few results, presumably as part of exhibits that discuss the man further.
With regard to sites devoted to Charles Babbage, he has been awarded a blue plaque in London which you can visit at 1 Dorset Street (more info: http://openplaques.org/plaques/3061) at the house where he lived for 40 years. This is though just the plaque, the house its self is not open to the general public and there isn't an information board.
I don't ...
You may have covered the options in your research. The digital National Library of Scotland offers the following, from its collection, The Scientists:
Lord Kelvin (1824-1907)**
Places to visit
Locations and visitor attractions associated with Lord Kelvin:
Belfast Botanic Gardens:
Lord Kelvin statue
21-25 College ...
In Swindon, you can find the museum of the Great Western Railway of whom Brunel was a chief engineer. As well as the story of the railway itself, it tells the story of how society thanks to the railway, and of Brunel's key role in the whole enterprise.
In addition to your research, Wikipedia suggests a few more options:
Watt was buried in the grounds of St. Mary's Church, Handsworth, in Birmingham. Later expansion of the church, over his grave, means that his tomb is now buried inside the church.
The approximate location of James Watt's birth in Greenock is commemorated by a statue. Several ...
It isn't about Turing in particular, but you can see a replica of the Manchester Baby, a computer that Turing programmed, and the first computer to store user-entered software in electronic memory, at the Museum of Science and Industry, Manchester.
The Tower of London has a section on the Royal Mint, which includes a small piece on Isaac Newton. The tower is definitely worth a visit if you are interested in political and military history. However, there is not too much scientific history there.