Hi Angie, I went on this trip last month. I think you might be staying in a different hotel so can't really advise much with that but overall the holiday was well organised and lots to do if you've booked all the excursions. Although it was quite early starts for us, you might be staying a bit nearer to some of the main areas so you might get an extra hour in bed :-)
We had a group size of 22 people, some had been away with Just You or with other solo companies before but for some of them it was their first time. Everyone got on really well and I'm sure it was a great introduction to solo holidays for the newbies, hopefully it has inspired them to carry on and book more trips on their own.
Our guide for the whole trip was Silvia, she was really good fun and looked after everyone, even organising local walks for the odd afternoon when we did have a bit of spare time. You'll have local guides as well for most of the excursions but Silvia stayed with us the whole time.
Make sure you have comfortable enclosed shoes as places like Pompeii and Herculaneum are quite rocky and uneven to walk around and you'll need something with a good grip if you're doing Mt Vesuvius.
Have fun 🙂