A few other people have suggested earplugs. I agree, I think this is a very good idea. Noise-canceling headphones might also be something to try, with quiet, soothing music playing to help drown out the other noises.
The reason that it's not right to try to stop these noises is because they are being made by people who are enjoying the activity that causes the noise: the kids are playing football (it sounds like they're playing in a park, which is appropriate for the activity) and the jackhammer is for construction which will result in a better garden that more people can enjoy. It's all good, it's just the sound that is not good. Most people aren't bothered by sound, and it's not fair to other people to expect that they always accommodate our comfort. It might be ok in some situations to ask the kids to play in a different part of the park, further away from you. But the best thing would be to try to block out the noise however you can so that you can be comfortable and the other people can still enjoy their activities.
_________________
You don't need to hide, my friend, for I am just like you.