Not being a lawyer as some seem to be on this thread, as I read the situation. Whilst the OP was driving well as in law with due care and consideration for other road users. The fact he had seen the cyclist riding towards him without lights, means in my mind he had a duty of care to insure that he did not continue in a fashion which would have further endangered the cyclist. However, if because the cyclist did have lights then if the OP had not seen him, then he could have a good argument for running him down.