Luton is the worst place I have ever had the misfortune to live. I lived in the Stopsley area (one of the better places to live in Luton), and whilst there, had my house burgled, my garden vandalised and they even tried to burn my garage down (but being "thickoes" they didn't realise that concrete and metal doesn't combust too well! However, they did burn the elderly ladies wooden garage down 10 doors up the road). The Arndale Centre has a significantly higher proportion of Chavs than most other shopping centres in the UK. The town centre car parks are dingy and badly lit - so much so, that when I visited London I would drive the 15 miles to Stevenage and catch the train from there (by the way, I'm 6' 1"). Also, one Saturday afternoon at 4.30 a girl was raped at the bottom of the stairs in the Arndale Centre and nobody noticed!! (this was 15 years ago.). My job required me to work there last year for a year, and if anything, it has got worse.
As Laurafoster pointed out, if you can go to Harpendon all the better - very posh, and good rail links. Also Flitwick, approx 15 miles to the north, again excellent rail links.
Sorry if this puts a bit of a downer on you, but Luton is a dump (sorry Lutonians).