For the tax year 2013/2014 this spreadsheet provides some interesting statistics for employees and employers.
Employee Salary Table (PAYE, NIC Employees, NIC Employers)
For employees you can find out what your take home pay is based on your annual salary and what your effective tax rate is.
For employers you can see the true cost of employing someone inclusive of Employers’ National Insurance Contributions.
Alternatively, these calculations can be performed using this tax calculator.