I'm traveling alone and got a pre book ticket in silent and clean I'm coming from Egypt. The most suitable flight I found was one arriving in Copenhagen at 2:45 pm Saturday 24 June add maybe an hour and a half until I make it to Roskilde so is that enough to have an OK spot? i necessarily don't want to arrive early than usual.
Yeah, you should be okay as S&C is only accessible to people with a pre-booking ticket until midnight.
If you are just one person it shouldn't be a problem anyway.
Keep in mind that it will be very busy around the time you arrive as the camping sites open at 16:00 so expect some queueing at the shuttle buses and entrance.
Make sure to go directly to the South entrance, you can get your official wristband later at one of the main entrances but you are allowed to get on the camping site right away wit your pre-booking ticket.
If there is an option to arrive earlier in Copenhagen on Saturday I would recommend it just to avoid the queues and join the pre-party in the waiting area.