I'm receiving more and more email requests from people who want to know if I can illustrate their book for them. I'm always flattered because it's always lovely to think that my work is in demand in any way, but I'm struggling to find the time to respond to people individually and take the time to explain how the publishing process works and why I'm unable to take on collaborative/self-published book ideas that don't come via my agent.
If your book is going to be self-published, there may be some illustrators on the SCWBI Facebook group who are keen to work on these types of projects or (if via Ireland) the Illustrators Ireland page.
Sarah McIntyre writes a wonderful post about this topic here offering tips and advice: https://jabberworks.livejournal.com/744387.html
The very best of luck with your book and wishing you all the success on your publishing journey!