A court transcript would cost £10,000 for this trial.
Ok, but the judgment is available for free, and plenty of news outlets have published live coverage of what happened each day at trial (often verbatim). This was obviously subject to various reporting restrictions so it's not a complete picture, but it's also not irrelevant, and gives helpful background as to the defence arguments, how the issues that people say are problematic were covered at trial, etc.
I'm not suggesting experts or anyone else doubting the safety of the conviction would need to have seen everything that's available in the public domain before raising concerns as that would be ridiculously onerous. I am, however, surprised at the number of people saying it's an unsafe conviction who haven't even read the judgment that examines the original judge's decisions and explains why they were upheld.
It seems to me unlikely that supplementary evidence with prior cases, proof of air embolism, counterpoint to unsuitable lab tests exists and was presented and has somehow gone unreported.
The defence did address the air embolism evidence, reliability of Evans, unsuitable insulin tests, though, and this was reported. Where each issue (and others) landed is covered in the judgment.
I'm not saying the judges are infallible - obviously these things do sometimes go wrong as we all know. It's just that going back to the actual conviction and the reasons given for it (and for rejecting the appeal) is the obvious starting point for questioning whether such a conviction is unsafe.