Multiple 24-Hour Visa Free Transit - Guangzhou to HK and then HK to Guangzhou

Hi, I just want to make sure I've interpreted the Visa Free Transit rules.

Is it okay for us to travel on UK passports using the 24-hour visa free transit if we:
- Arrive 1st April at 6pm to Guangzhou Airport from Melbourne;
- Take a Train or Ferry to Hong Kong within 24 hours;
- Spend 4 days in Hong Kong;
- Take a Train or Ferry from Hong Kong to Guangzhou on 6th April at 2pm;
- Depart 7th April from Guangzhou Airport at 1pm for London (i.e. within 24 hours).

Just trying to ensure that the timing and the use of a Train or Ferry are going to be allowable.

Thanks.