It's definitely not too late to start!
If you're planning to apply for University, you'll write your Personal Statement at the very endof Year 12/start of Year 13 so you have 3 and a half years to do some activities. If you don't want to go to University and will apply for a job straight after school, it's still 2 1/2 years before you can apply to most places, so again, plenty of time.
Don't do a club just because you think it will look good though. You need to have at least some interest in the activity/ies you choose to do, or you'll end up hating it and quitting after a few weeks. It's also not just "I do football club after school" that looks good, it's having positions of responsibility within that - being Captain of the football team, or being a regular player for the school, or organising a club for younger students. This is where liking what you do, and starting it now (as opposed to when you start year 12) is really helpful.