What rudestuff says is correct. How much training you will have to do depends largely on how much single time you have, how much of it is solo and what that solo consists of. However, the final decision will rest with the HOT at your chosen DTO/ATO, since there is no laid down procedure. He/she may also have to justify how much or how little training was done, if asked by the CAA.
There are no SEP initial exams, only PPL. They are not online until October, but you won't be able to access them outside of an ATO/DTO. If you have ATPL writtens you don't need them anyway.
I've been asked countless times by pilots such as yourself to carry out the process, but hardly anyone's actually come to do it because of the cost.
PM if you wish.