You can do it as Billy Moat told you, wrap your <img> and <h1> in a <div> and use float: left; to float your image to the left, set the <div>width and than set a line-height for your h1 and use <div style="clear: float;"></div> to clear your floating elements.
.header{width:100%;
}
.header img{ width: 20%; //or whatever width you like to have
}
.header h1{
display:inline; //It will take rest of space which left by logo.
}
This is my code without any div within the header tag. My goal/intention is to implement the same behavior with minimal HTML tags and CSS style. It works.