Has anybody dealt with headout? A British ticket reseller. Ie- were tickets they bought there valid and accurate for what they claimed to be.ie “escorted entry “ to the museum and then you can spend as much time there as you want?
I have no experience with that entity. Is there is reason you wouldn’t just buy the tickets directly from the Vatican Museums website? I’ve been several times and always bought directly.
What day(s) are you in Rome? Have you checked to see what is available on the Vatican Museums website? The general-entry tickets may be sold out, but there might be a Vatican tour available. It would cost more, but possibly not all that much more than the company you've uncovered is charging, and you wouldn't have any doubt about getting into the Museums with a ticket purchased from the source.
The OP is already aware of the official website:
So I'm guessing general-entry tickets for his Rome dates in June have already disappeared; they've been doing that very, very quickly once they become available. I've no experience with headout but online reviews aren't especially positive. I'll leave it at that. honfleur25, as already recommended you might consider booking a more pricey but still-available tours on the Vatican's website which might still be available for your dates. You can spend additional time at the museums on your own after the tour is over.