<form action="http://test.com" target="_self" style="display:inline">
	<button type="submit">
		<img src="#" alt="Зонтик" style="vertical-align:middle">
	</button>
</form> 

<form action="http://test.com" target="_self" style="display:inline; margin-left:10px">
	<button type="submit">
		<img src="#" alt="Зонтик" style="vertical-align:middle">
	</button>
</form>