Newcrew if you think you won't make it you probably won't. CX is all about confidence - we are the best you know!
Anyway to answer your question - very very few fail initial training. With your experience surely you will be ok. It s the command upgrade that gets about 30% of the guys the first time around. If you're joining from SA and you want to join on the freighter or FO on pax you have to take a base. Do you have a Euro/US/ Aus passport?? Otherwise you might have to join in HKG as an SO.....which is a bit silly with 6000 hours since you can go elsewhere and make twice the money.