you'd need to talk to your local council.
yes you do need to apply and i believe you can be on the list even if you aren't homeless, because you're at risk of losing your home ?
Our council has the bidding system, which means that you get more choice with you home (not much though)
If you go to your local council and say that you'd like to be on the housing register (i think thats what its called) they should give you a long form.
If you are made homeless (by loss of you job etc) then you would be a higher priority i believe.
Also I rent privately but claim housing benefit. Are you doing this, because it would be a very good idea to if you are on a low income
hope this helped. good luck x