Change to css and design to make a template fresher

My current website designed back in 2012 and needs a serious refresh. However, whilst this is happening I just want to tweak the existing design to make it cleaner and more modern, taking out a number of graphics on the header.
Attached is the rough designs of the new desktop and mobile views (you can view the existing website at www.primoregistrations.co.uk) so that you can see what needs changing.
The website was built on kohana. I have got access to any css and view files on the sever to change.