Whitby,
I think the reason it has taken a while for someone to answer is there is a long answer and a short answer and you really need the long. I am not quite sure what the tool is that you are referring to on Moz, but you have some issues here. I will ignore UI/UX and just speak quickly to SEO. First, never have an entire site that is essentially a single page.
You have multiple meta descriptions and it appears that each property has been coded as a page but it is not. The "H1" is over 700 characters and appears to be pulling from multiple places, etc. Almost everything is Bold or Strong. etc
I used a site: search operator and you are showing about 165 pages and I have no reasonable way of knowing how to get to them without using a site: (unfortunately, I am not your customer and they have no idea what that is). Your entire sub directory structure is odd to me as in some places you use .../subject of post/whitby-blog and others you use the opposite, etc.
I have to ask if anyone is looking at your Google Analytics or WMT? Your analytics code is not before the closing head tag where it should be and you may or may not be getting good data.
So, Given how you state they explained the problem I think they are at least worth a look but I would get a second and third opinion. There are some great SEO's in the UK. (Several are regulars on Moz and if you PM me I will send you a couple I have worked with whose work I can attest to.) You need some real help here if this is going to rank for you over time.
Sorry, wish I had better news.
Robert
He is really better served using New Port Richey. I lived in Tampa and my business was in Clearwater. When he first mentioned Trinity, I had to look it up.