We might try a PoD of mid-1950, Korea evolving differently, such that US treated the place with the same disinterest with which it dismissed France's 1954 request for AW intervention at Dien Bien Phu. US watched the colonial oppressor ignominiously ejected.
Say, USSR vetoes any UN police action, 6/50. US stands idly by as the South is pushed into the sea, US over the hills and far away.
Let's have Churchill still winning 10/51 Election, but now convinced Ike was not his friend in any similar need: say, PRC moving on to revive the Emergency in Malaya, so threatening everywhere East of India, South of Japan...so ANZ. (In real world he wasted time hoping he could rent or borrow B-47/Mk.5 "the Article", and not need to divert AEA from power generation). Let us now assume he places more orders sooner for Mk.1 V-Bombers and for Red Beard gravity fission Bomb. Then what?
All British historiography misreads 8/46 McMahon Act, theft of our Bomb. No. Truman/McMahon denied USAAF Gen.Dr.Strangelove any access to AW, which was just as well over Berlin, 6/48, Korea 11/50. MoSupply Sandys spent much time from 1/53 stroking Ike's team to extract GW and AW data. So, next PoD: that all that effort fails: UK (+Canada/Oz/NZ): alone again. Ike's US is not gendarme of the world, UK gets no AW privilege. Ike does however, as in real, transfer the AW inventory from AEC to his Forces progressively through his tenure, but none of the realworld target/data collaboration happens. So USAF asks us nicely if they can hold Bombs near that twee Victorian seaside resort, Margate, and we choose to tell them to get lost...unless we can play too on your Big Bangs.
You see the conundrum: if US/UK are Allies we can, nay we must rely on their AW umbrella. If we are not...then we are fundamentally stuffed, once Uncle Joe builds Klaus Fuchs Bomb. When WSC told Sir Wm.Penney to do an H-Bomb, historian Lorna Arnold has him meeting AWRE's Brains Trust to ask: does anyone know how it's done? No answer was the stern reply. It took them 10 years (5/47-9/57) to equip RAF to deploy 24 copies of Fat Man. Their solo "megaton weapon", Violet Club, was more Threat to Rutland than to Russia.
So I resist OP's premise of a possibility to have done more. I agree #2 - where do we get more fissile material, and add: and the rest.
