I'm at Hatfield and trust me the chants aren't anywhere near as bad as this article makes out. It honestly is just a bit of fun and if anything it helps all the Hatfield freshers to bond more as a group, I found it all really amusing and also really fun to chant back! In terms of not getting to sleep that's just because some of the bedrooms are on the Bailey and it is noisy during Freshers Week. The Freps are there all week, both from Hatfield and other Colleges, and if the chanting did get out of hand they'd control it.
Also please don't be concerned about coming to Hatfield from a state school background! It may have a reputation for being a bit 'public school' but I'm from a comprehensive school and I LOVE it - there's something for everyone and everyone you meet is so so nice.