In the US, you'll sometimes hear "that's not my speed" in situations where a person wants to refrain from doing something. So, if someone asks a non-drinker if she'd like a glass of wine, she might say, "No, thanks, that's not my speed." I've never really heard it used in the positive (i.e. "That's my speed" though I suppose it might be). That said, I don't hear it used very often. If I wanted to express that sentiment, I'd be far more likely to say "No, thanks, that's not really my cup of tea." (And I'm not yet 30, so I don't think that's too old-fashioned). Again, one doesn't often hear it used positively.
"That's right up your alley" has a slightly different sense. I'd use it to encourage a friend to apply for a job I'd seen advertised: "Hey, Jane, you should put in an application for that position. It's right up your alley." Meaning that it seems to fit Jane's particular skills or interests.
Literal example of my speed:
I'm given a huge race horse to ride (who is, by the way, no longer racing because he doesn't like to stop). I'm left traumatized, just by the thought of going head-first into low brambles or over a fence by a sudden stop from a horse who doesn't want to jump a fence. I get back to the barn, and they swap my horse out for a pony--one who doesn't really mind who gets on its back. I say, "This pony is more my speed!"
As a metaphor:
I spend the day scraping paint off the side of the house. I get sunburned and have big knots in my back muscles and callouses on my hands from the job. The next day I am treated to a boat ride on the river, and I say, "Wow! This is more my speed!"
Literally up my alley
Someone stops to ask the directions of someone else's house. I say, "Oh, I know her, she's just right up the street (or she's just right up the alley) from where I live!
Metaphors using up my alley
I am a championship horseman. I am on vacation and one of the activities we do is going to a dude ranch whereI am introduced to the aforementioned race horse. Because of my experience, I would say, "Well, howdy doody! I do believe this activity is right up my alley!"
My friend is frustrated on the most efficient way to take paint off the side of a house. Because I paint houses for a living, she calls me. She figures I can give her some pointers, because painting houses is right up my alley.