Indeed. Your best bets are either to find a local LARP group (give us a location and we’ll probably have members from there on these forums) or to turn up early at the events and get some practice in.
Most groups/nations will happily set to for a spot of tuition/practise/sparring. If you need extra room, come to Dawn, we have a sparring ring (“The Glory Square”) for just this sort of thing
Bear in mind there’s a wide spectrum of what is known as “hard skills” (how skilled you are at LARP fighting, as opposed to what’s on your character sheet).
There are folks who ONLY do larp-fighting at Empire, at not much of that. There are those who do LARP on a weekly basis and are well practised. And there are those skilled fencers and HEMA fighters able to adapt their skills and experience, coupled with extensive LARP fighting techniques, to become very good at it.
It’s a big spectrum. Whatever you do, you’ll be better than some, and worse than others.