Good afternoon,
I am new to Freelancer, however I have done alot of work on other Freelancing websites - my work being highly focused on Wordpress. I am UK based.
I believe you are referring to the white space under your main content on the homepage? This is not your sidebar causing this... it is your main content area as it has a set-height specified.
I can make this change within your CSS file this afternoon.
In order to complete this work I would need temporary access to your Wordpress Website, and potentially your FTP (depending on your theme file structure).
If you have any questions, please do get in touch.
Kind regards
Charly