HM Courts and Tribunal Service and BIS have produced a consolidated version of the Employment Tribunals Rules of Procedure 2013 and amending legislation, which is up to date as at 17 February 2015. However, before the end of the last Parliament, the draft Employment Tribunals (Constitution and Rules of Procedure) (Amendment) Regulations 2015 were published and, once passed, they will amend the employment tribunal rules on postponement.
The rules on how cases are handled in employment tribunals, from starting a claim to what happens at a hearing can be found here.