pregnant

So I had sex with a condom like 2 weeks ago and he pulled out. My period is now 8 days late. I've ordered a really cheap test from Superdrug but it hasn't come yet and I'm nervous to take it as I'm not close enough with my family to tell my mum that I'm sexually active. 
Anyway my question is are cheap tests less effective than expensive ones? Am I more likely to get a false result?