You can (and sometimes do) work until 23:59 the day before your leave. You will get one day off after your leave (regardless of how long it is) to make sure you are back in Dubai the required 12 hours before your next duty starts. Sometimes you will have to travel back on your last rostered day of leave- you can be at work at 06:00 2 days after your leave finishes.
You can take 4 blocks of 10 days off but none of it could be peak. You can't take 4 blocks of 7 days as that wouldn't add up to 30 days- two blocks of 8 days and 2 of 7 would work but again none of it could be peak.