Hello Jenny an a warm welcome to you.
I have done 8 JY tours there is a video link on here of me, Cindy NIXON and another from Lovely Lesley have a look at them might help you.
MY 1st JY tour was USA, so I jumped straight in. You will be a younger traveller but that's fine I am sure you will be made welcome. I have been to Prague (not with JY) and it's a really great City break to explore. The China trip is very popular but it is a very busy tour.
Honestly there is nothing to be nervous about these tours are all very good, and you are looked after along the way, it's a very safe way to travel for ladies. I would say to you, go for the tour that you really fancy doing, there's a big world out there so go and explore it, we only live once.
Have fun
Good Luck
Cindy