I dont have a wireless account but my laptop has built in wireless.
If I go somewhere that has "free wireless" access, eg a cafe, will my laptop automatically work with this network or do i need to have an account with my own ISP as well?
You would be using their network so no you would not need an ISP I believe.
But you would need a wireless card but yours sounds like its inbuilt.
The best way is to go there and check, you should get a network notification