SEO Error Fix for Custom Site

I need an expert to identify and correct errors on my custom HTML/CSS website that are negatively impacting SEO. I'm currently using SEMrush for my SEO efforts.

Requirements:
- Expertise in SEO and familiarity with SEMrush
- Strong skills in HTML/CSS
- Experience in fixing common SEO issues like broken links, slow page load speed, and duplicate content

Ideal Skills:
- SEO knowledge
- HTML/CSS proficiency
- SEMrush experience
- Problem-solving skills

Please provide a detailed plan and timeline with your bids.