Given the Tories track record in foreign affairs, from cosying up to chinese and russian dictators, failing to rebuild relations with european allies and even not funding defence of the nation correctly after Ukraine, i'd not have any concerns about Labour.
The civil servants in govt departments will still be there and opposition politicians do keep up to speed with world events.
But the main thing in regard to your question is that the UK is a bit player, we are no longer in any political bloc, our military is poor & we ve slashed foreign aid.
Labours biggest issue is going to be domestic, council funding, roads, health, education, skills, immigration, real affordable housing - esp to rent.
Atm they don't appear to have any publicly available plans to address these issues & yes i have looked at their website, its just a series of wish lists.