Most Phase II students have a position or a scholarship from external sources, not from BMS directly.
At most 25% of the Phase students is funded by the BMS Phase II scholarships. When applying for Phase II scholarships, your prospective supervisor has to verify why no external funding is available.
For BMS Phase II scholarship eligibility criteria, the official BMS webpage gives information. (Chapter 8) These are necessary but not sufficient conditions to get the BMS Phase II scholarships, according to the current financial situation of BMS. But typically, if you have an average of Phase I courses better than 1.5, you will get a PhD scholarship either from the BMS or from some of the certified units. If you have average worse than 1.5 but better than 2.5, you still have a chance to continue for Phase II if you can find external funding with the help of your supervisor.
Therefore the most important thing is to find a supervisor for the PhD!
If you have to encounter some months without funding after the end of Phase I, you can apply for gap funding at the BMS. The gap funding lasts until at most 6 months.
Note: Any change in your funding that involves the BMS giving you money (BMS Phase I scholarship extension, BMS Phase II scholarship, gap funding) has to be decided by the BMS Board. There are no board meetings in March, July, August and sometimes even not in September.
If you expect to have a funding gap (e.g. you have Phase I funding until September but you only finish your Master's in October), contact the BMS Liaison Officer of your university in advance in order to avoid this gap.