Well, in the 3rd year, there are double the number of places. Also, the 3rd year is the most important as they take pre-reg's only from those who have done a 3rd year summer placement.
If you do do a 1st or 2nd year placement, make sure you try real hard, so maybe they will take you on for a future 3rd year placement.
Btw, you can't apply yet, as the application is not open yet, You will just have to wait for the uni to tell you when you can start applying. It doesn't matter if you apply early or the day before the deadline, you have an equal chance of getting in (providing you haven't rushed your application.)