52 x �300 = �15600. Entering that annual figure into the calculator, here
http://www.thesalarycalculator.co.uk/salary.ph p
yields a weekly take-home figure of �239.25
Remember that there may be additional (non-statutory) deductions from your pay. In particular, if the company operates a contributory pension scheme, your pension contributions will need to be deducted from the figure above. Additionally, some people have such things as union subscriptions automatically taken from their earnings, which will further reduce take home pay.
Chris