Your Facebook profile is only available to people on your friends list and anyone in the network you're in, if you're in one.
For example if you were in the Kent network, then anyone in the Kent network could see your profile, although you can choose how much of your profile they get to see, from all to none should you so desire.
You can't tell who has been looking at your profile unless they leave a message - no doubt the Facebook admin team can, but a normal users won't be able to