New professional website where the website can be very easily updated by a lay person

General information for the website: we already have our website and content, just need to move it to a platform which is a lot easier to manage!
Description of every page/module: Our existing website is at:

www.imperialclaims.uk

I'm uncertain how to manage the current website. So, I want it all pretty much copying and pasting onto a new platform and which which is extremely striaghtforward to personally manage.

I want a blog to be added. I want a question and answer section to be added. So, I need to be able to add pages and photos and videos by myself. That is what I need, the ability to update the website by me, just a lay person with no real previous website skills or knowledge. But, I still want a very professional website, like the existing one!!
Description of requirements/features: Please see above. I think this covers everything already?
Extra notes: