As far as the concern about the SOY support package for UK Payroll, it simply means that you want to apply some support packages that relates with the new functionality for the taxation year of 2013/2014, seems to be not for the all packages, it will be compatible with the year of taxation ends and the year of taxation starts that support packages for SAP HR, for this you must be confirm about all the necessary product that are deployed and that the sequence of applying is observed very cautiously. It must be supportive to reappearance for the profit of someone who is new to this process.
As you are here for the Start of year (these are the new rates with which your question is exactly directed, the main SAP Note is 1796768.The same in the case of RTI, the main note is 1810145. Next you have to implement SAPK-60459INSAPHRCGB support packages, you have to implement SP before you are ready for the 59 SAP level, you must have to maintain the ER_HR .Besides this you have to examine which stay remain with HR/PY support Package.
As far as this concern ER_HR SP level is still compatible with the 57 SP level so it resides with the updating in SP 57 to 59, you have to update ER_HR with it too and next you should have to opt an account of CLC’s for payroll (Country Legal Change) levels for every component SAP_HR.