My boyfriend and I had sex earlier so I took a Plan B after 1 hour. Will this still work?

Plan B is not as effective as regular hormonal birth control, but it can be worth a try in an emergency.

The only emergency contraceptive pill that is proven can prevent pregnancy during the 24 hours around ovulation, is Ella (Ulipristal Acetate). You can see that on the Ella website.
However, even Ella isn't guaranteed to help.

Here in the UK, if you are in your fertile days of your menstrual cycle, pharmacists will give out Ella instead.

It's possible Plan B might help even if you were at that time of your cycle, but it has not been proven that it can, unlike Ella.

To help prevent condoms splitting, you can nip a couple of centimeters shut, at the tip of the condom, as you roll it onto the penis, making sure no air gets trapped inside. This leaves you an air-free pouch, hanging a little off the end of his penis, for him to ejaculate into, without the condom bursting.