Update
Yes I should have just tested before asking - But it may be helpful to others
Had to create a docker file, base it on the n8n image, and add the steps I wanted such as
FROM n8nio/n8n:latest
RUN apk add --update python3 py3-pip
RUN npm install -g require
RUN npm install -g humanparser
and then create an image using
docker build n8n-custom .
and then usee n8n-custom in my docker-compose
and add the modules into the NODE_FUNCTION_ALLOW_EXTERNAL= env variable in docker compose