Well my bills over the past few years have averaged about the following:
TV License - £36.89 a quarter
Virgin (TV, net, phone) - £50 a month
Electric - £35 a month
Gas - £16 a month
I'd say you'd be pushed to get it all within £450 a month, but £500 should be just about doable. It's nothing at all if it's between 2 of you!