I need some issues fixed on my website (CMSMS based site)

The main problem is with the image upload facility which no longer works (at the backend). However there are several issues creeping in as time goes by, such as the recipe loading page seems to only work intermittently, especially on computer vs phone. I think the site needs a good maintenance check? This is the website: www.balancedplate.co.uk It’s not a wordpress site. I want to get the site functioning fully to then be able to do more with it. thanks