I know from talking to MORE than a few people that had PAYE jobs up till reciently. They jumped into the self empliyment market almost immediatly.
They all found that the expected monies or returns were not forthcoming and went back to sign on.
They were told they were entitled to nothing as they were now classed as self employed.
They have the right to appeal, but that will take a considerable length of time.
You then have the option of not registering and carrying on your business on the black economy. However, one of your customers may want a receipt to put in against their tax returns (particularly if the expence comes from your training class).
I hope I have given you a few points to consider.