Aside from any School/Branch directives or policies, doing an Occupational transfer in your case would likely go as follows:
1. You fail the MOC trg and would likely go to see a PSO (Personnel Selection Officer) and have to pick from a list of trades that have opening from the Reassignment List (published monthly IIRC), of course your CFAT scores would affect what ones you might qualify for.
2. You haven't completed your QL3 yet and are somewhere between BMQ-QL3 qualified. You would submit a request for MOC reassignment BEFORE you were QL3 qualified and submit if up your CoC. It would be reviewed by the proper authorities (PSO, DMCA, Career Manager shop, etc) and be approved/denied. This would be in accordance with CFA0 11-12 Occupation Transfer of NCM - Regular Force.
3. You complete 48 months of service, have a QL5 qualficiation level, and apply for one of the Occupation Transfer programs (COTP, VOT) again IAW CFA0 11-12.
4. You don't like any of those options, and do not enrol, or put in a VR before completing trg, again it would go thru your CoC and a decision would be made.
I'll say this...you are making a judgement on the work of an LCIS Tech and SigOP without having done, or even *seen*, that work at this point in time. Both those trades, to some extent, work together to achieve a common goal; communications for the unit(s) they support.
Keep an open mind. You may find that if you ended up on the *tech* side, you wish you were on the Operator side. But you'll never know until you get there. I thought I was going to like my last MOC ( a tech trade) and I didn't once I got there. I wasted mine and the CFs time and money.
Don't shut your eyes to any aspects of the C & E branch, thats my advice. Something drew you to it in the first place, right?