Trade agreements with Europe may be one thing that Starmer is able to improve

There's a pretty good chance of that, and other EU-related things. Johnson, and to a much lesser extent May (due her weak Parliamentary position), forced all negotiations with the EU into ones based on mutual distrust. To say something nice about Sunak, he went some way towards thawing that, especially in the earlier stages of his premiership. I have hopes that Starmer can go further in that respect.