Finish 6129 & 6089 (pass), if you have the required number of days (70+) experience working with gas under a GSR engineer, apply to a ACS center & pay for any further training you feel you may require & the ccn1 assessment, take it & pass, then book the assessments you require i.e. boilers, cookers, fires....... etc apply to your training agent for the sum of money they have set aside for this if you are an apprentice, exchange copies of your certs for this money. (I think its just boilers that is paid for out of these)
See it's easy isn't it. NOT.