Numerous times but I can’t recall who I used (to Sydney). Typically when I ship internationally I try to get a pick up late in the week and use an Express service so that the guitar is on the air over the weekend, in customs by the start of the week and delivered later that same week. If it spends a couple of days over the weekend in storage I don’t think would be a problem.
I would be more concerned about the season ie waiting a while and getting past any extreme heat in Adelaide or snow in the UK. That is, I would be more worried about having a guitar in then back if a truck at 40 degrees all day than sitting in their distribution depot over a weekend.