Looks like you’ll almost certainly have to do a qualifying event unless you want to chance the lottery. Which means you’ll need a trip to the States to ride one of the QEs the year before you intend to ride the Leadville. Looks like the qualifying events are also run by the same company/organisation.
Could work out quite expensive: two trips to the States plus two registration fees + costs whilst you are in the USA.
Any reason for the Leadville or does it happen to be one you’ve heard of? Not trying to put you off, just interested, I do just as daft stuff and I’m somewhat older than you!