If you do snag pupillage and tenancy, and should the stars align sufficiently for (1) you to last long enough in practice, (2) your clerks to throw interesting cases your way, and (3) you to acquit yourself well in arguing them, you may well just make QC.

Statistically, there is a higher chance of making QC than SC. There is a list of all appointed SCs ever. Contrast that with the no that get admitted as A&S here every year since they started appointing SCs. You have a better shot at winning toto.

The difficulty is even becoming a practising barrister in the first place. You have all the hurdles identified to clear, and they are neither wrong nor inconsiderable.

If you can, please watch QCs and SCs in action. Courts have public galleries, if you didn't already know, and the hearing lists are also public info. Go spend some time in the courts, watch how the masters work their magic, realise how much time/experience that that requires, and come away inspired to try yourself.