Yes, angels have free will like us. When Satan chose to stop obeying and worshipping God, and vaunted his own pride, that was a free choice, with the consequences that followed. One third of the angels chose to follow him. (See Rev. 12:4)
What sets apart angels from us is that we can be forgiven and restored, and they can't. To follow God or not was a one-shot deal for angels, as far as we can tell. 1 Peter 1:12 says that angels "long to look into these things" (salvation and grace), which are not available to them.
Hope this helps.
Perhaps you could also tell me what will happen to the Angels that sinned. Surely, God will not allow them to continue in their evil ways for ever?
Right. Revelation 20:10 says, "The devil. . .was thrown into the lake of burning sulfur, where the beast and the false prophet had been thrown. They will be tormented day and night for ever and ever."
Before this final judgment, however, there will be a 1000-year period where the fallen angels are held in bondage in some sort of Abyss. So the earth will find out what it's like to be free from demonic influence for a millenium before Satan (along with the other fallen angels, I presume) is released (Revelation 20:2-3).