There are folks on this forum whose first bike was the Bobber but it isn't necessarily the bike it's the rider... and the other road users. You need to be prepared for their dangerous and inconsiderate driving. That said, if you get enough of the right training and maybe read a good book or two you shouldn't be any more at risk than the rest of us Bobber people. This is just my 5¢ though.
Good book - Motorcycle Roadcraft, The Police riders Handbook. Try and get the early version.
Welcome to the forum. I'm on the other side of the pond so I don't know much about British riding. (I have ridden in Ireland.) I've been to London sever times and even driven in London with an American car. So all I have to say is good luck and be careful.
I learned to ride 40 years ago on a small dirt bike. It taught me a lot about bike handling. That said, one advantage of the Bobber is that it is not a tall bike. It has a low center of gravity.