Hey, I'm a first year student at Lancs,
Don't worry about the nightlife, I had the exact same worry haha. I imagined Lancs being some old weird farmer town. Granted there's not as much as London, but really in a student town you don't need so much, as it's the people that make the difference, not the place! But Lancs is really geared up for students anyway- nearly all places do student nights, student offers etc etc.
But there's loads anyway, there's 2 Wetherspoons, loads of pubs, theres the main student night club Sugarhouse where everyone always ends up in so that's always buzzing, there's Elements, Revolution, Lounge, Lost, Hustle, V-Bar, Mint, as well as a 24 hour McDonalds for drunken food haha! I think there's even more than that going on too, they're just off the top of my head.
Not to mention the bars on campus! Each college has one.
And all colleges and societies do socials to other places- so far for me there's been ones to Liverpool and Manchester.
So really I can't complain