Hi there and
to the forums!
Deborah has given some great information
I'd like to add is that with only one bird, dander is generally not a problem.
I have one budgie and she's been with me for four years now; with just regular vacuuming once or twice a week (every other day when she's moulting) and cleaning the cage daily, her dander hasn't affected me or others in my family at all, one of whom has severe allergies. So I don't think you need to worry
Also, since it would be your girl's first bird (even though you'd obviously be involved as well), if you had a choice between breeder raised American budgies and breeder raised English budgies, there really isn't a difference. English budgies are often considered to be more laid back, but all birds have their own personalities so that wouldn't really be a factor.
The reason American budgies are considered more difficult are because, sadly, they are the type mass-produced in bird mills for "big box" pet stores like PetCo and PetSmart, and have no human (or bird parent) interaction at all, making them flighty and harder to tame than a bird who has been properly socialised by a breeder. So it's really not the type of bird at all, it's the way they were raised, as well as their individual temperaments and behaviours.
I'm glad you're getting your new little one from a reputable breeder as we don't recommend buying any bird at commercial pet stores as it promotes their bad practices of budgie care
I'm glad you're finding the forums helpful so far and if you have any questions after reading through everything, please do ask as we'd be happy to help
Hope to see you around and it's great to have you with us!