Images in footer on specific pages

Question

I want to include a small logo on particular pages in a large document, in the left hand side of the footer. The way to do this seems to be with fancyhdr's alternate-able styles.

I've gotten close to what I need, but I have 2 questions:

1. The header style for the new logo pages is a direct copy of the IHA-fancy-style, but I have been setting the \lhead and \rhead on a chapter by chapter basis, and changing the text style. How can I change my current set up to apply the headers to the new pagestyle too?

2. How should I be positioning my thispagestyle command, when an image is set to use a full page with the [p] parameter of the figure environment? It wants to apply to the page before or after it seems.

I hope this is clear enough, I'm struggling to explain what I'm trying to do in my own head, so I've no idea if this makes sense now!

Here's a MWE of what I have so far (note there is a specific filepath for the logo if people try to re-run the code).

You should see from this output PDF, that the page with the Logo on, is lacking the headers from the rest of the chapter/document, and isn't the page with the figure on.

\documentclass[a4paper, oneside, 11pt]{report}
\usepackage[left=4cm, right=2cm, top=1.5cm, bottom=2.5cm]{geometry}
\usepackage{lipsum}
\usepackage{graphicx} 
\usepackage{fancyhdr} 
\headsep 25pt
\headheight 20pt
\setlength{\topmargin}{0pt}
\setlength{\textheight}{670pt}

\fancypagestyle{IHA-fancy-style}{%
  \fancyhf{}
  \fancyhead[LE,RO]{\slshape \leftmark}
  \fancyfoot[LE,RO]{\thepage\ } % Custom footer
  \renewcommand{\headrulewidth}{0.4pt}% Line at the header visible
  \renewcommand{\footrulewidth}{0.4pt}% Line at the footer visible
}

\fancypagestyle{augment}{%
  \fancyhf{}
  \fancyhead[LE,RO]{\slshape \leftmark}
  \fancyfoot[R]{\thepage\ } % Custom footer
  \fancyfoot[L]{\raisebox{-0.1cm}{\includegraphics[height=0.5cm, clip, trim={100 100 100 100}]{/path/to/mylogo.png}}
}
  \renewcommand{\headrulewidth}{0.4pt}% Line at the header visible
  \renewcommand{\footrulewidth}{0.4pt}% Line at the footer visible
}

\begin{document}

\pagestyle{IHA-fancy-style}
\lhead{\textsf{Chapter 1}}
\rhead{\textsf{My First Chapter}}
\lipsum[1]
\newpage

\lipsum[2]


\thispagestyle{augment}
\begin{figure}[p]
\includegraphics[width=\textwidth, height=\textwidth, clip, trim={0 0 0 0}, draft]{/path/to/dummy/image.png}
\end{figure}
\newpage

\lipsum[3]
\end{document}

EDIT

The answer below does solve the problem for the minimal case I posted, but raised other issues when I brought it in to the full document.

2 issues mainly:

Firstly, I can typeset the document correctly once, but when it comes to a second time in order to populate the ToC, I'm now getting this error:

Undefined control sequence.              # Pointing to my document.toc file
\f@ncycolh ->\sffamily \myleftmark       # I added sffamily to the header in the answer below, but its a valid command
                                   \strut 

which points to this line in the ToC file, though I can't see that there's anything wrong with it specifically

\contentsline {subsection}{\numberline {3.3.2}Harvesting}{78}{subsection.3.3.2}

Secondly, when I include my Appendix Chapters (even with a \pagetyle{plain}) I get this error:

Use of \reserved@a doesn't match its definition.
\new@ifnextchar ...eseverd@d  = #1\def \reserved@a { 
                                                    #2}\def\reserved@vb {#3}\f...
 l.685  ...{Chapter \ref{appendix1}}

Answer 1

I modified \@chapter to automatically set \myleftmark to the chapter number and \myrightmark to the chapter name.

Note that report class is one sided (default), so there are no even pages.

\documentclass[a4paper, oneside, 11pt]{report}
\headsep 25pt
\headheight 20pt
\usepackage[left=4cm, right=2cm, top=1.5cm, bottom=2.5cm]{geometry}

\usepackage{lipsum}
\usepackage[draft]{graphicx} 
\usepackage{fancyhdr} 

\newcommand{\myleftmark}{}% reserve global name
\newcommand{\myrightmark}{}% reserve global name

\fancypagestyle{IHA-fancy-style}{%
  \fancyhf{}% remove default
  \fancyhead[L]{\myleftmark}%
  \fancyhead[R]{\myrightmark}%
  \fancyfoot[R]{\thepage\ } % Custom footer
  \renewcommand{\headrulewidth}{0.4pt}% Line at the header visible
  \renewcommand{\footrulewidth}{0.4pt}% Line at the footer visible
}

\fancypagestyle{augment}{%
  \fancyhf{}% remove default
  \fancyhead[L]{\myleftmark}%
  \fancyhead[R]{\myrightmark}%
  \fancyfoot[R]{\thepage\ }% Custom footer
  \fancyfoot[L]{\raisebox{-0.1cm}{\includegraphics[height=0.5cm, clip, trim={100 100 100 100}]{/path/to/mylogo.png}}
}
  \renewcommand{\headrulewidth}{0.4pt}% Line at the header visible
  \renewcommand{\footrulewidth}{0.4pt}% Line at the footer visible
}
\pagestyle{IHA-fancy-style}

\usepackage{floatpag}
\floatpagestyle{augment}

\makeatletter
\let\@oldchapter=\@chapter
\def\@chapter[#1]#2{\@oldchapter[#1]{#2}%
  \xdef\myleftmark{Chapter~\thechapter}%
  \xdef\myrightmark{#2}%
}
\makeatother

\begin{document}

\chapter{My First Chapter}

\lipsum[1]
\newpage

\begin{figure}[p]
\includegraphics[width=\textwidth, height=\textwidth, clip, trim={0 0 0 0}, draft]{/path/to/dummy/image.png}
\end{figure}

\lipsum[2-16]

\end{document}