Have you seen this website, you want section 1.
https://www.gov.uk/government/publications/tax-and-tax-credit-rates-and-thresholds-for-2016-17/tax-and-tax-credit-rates-and-thresholds-for-2016-17
I'm not a accountant, but you'll need also to factor in other stoppages as well, e.g. NI contributions and workplace pension as these too will have an effect in the extra 'money in your pocket' which I'm guessing is at the root of your question?
i.e. how much more you can spend on trains
Edit: it really does help to post the link
Edit 2: with all my mucking about editting, I was beaten to it by a few mins.