i wouldn’t worry too much about how hard it would be, i would be concerned with how much you enjoy it!
history is such a tough a level but my love for it drives me through.
also, consider what you’ll do with the a level, i took graphics as i loved it and i enjoy those lessons wholeheartedly but it doesn’t work in my favour for my oxbridge application!
consider it holistically, but if you like dance go for it. you sound like you have the capacity to be good at it too!
(plus, if it’s too much for you you’re typically given a 2 week period to change course in most colleges)