Hi Natasha and welcome to WCC! G6 would be a good place to start, though with your solo pace you might find it not quick enough. Give it a try and see - you can always progress to the next group.
Hello Natasha
This link will take you to the club’s Road Culture description. Start here at G5. Then come out for the G5 Wednesday and Saturday rides. Within those 2 rides are people with tons of experience who will help you.
Hello @Natasha_Ilincic
Remove your tube from the front wheel, maybe that stem nut is inside the rim. Otherwise replace the tube with a proper length stem.
Brian Legge