Install the required tools

sudo apt-get install squashfs-tools syslinux-utils

Download the ubuntu iso

wget http://releases.ubuntu.com/18.10/ubuntu-18.10-desktop-amd64.iso

Setup iso_file variable

export iso_file=ubuntu-18.10-desktop-amd64.iso

Extract the image and mount it

mkdir mnt
sudo mount -o loop ${iso_file} mnt/

Extract the filesystem.squashfs

mkdir extract-cd
sudo rsync --exclude=/casper/filesystem.squashfs -a mnt/ extract-cd
mkdir squashfs
sudo unsquashfs mnt/casper/filesystem.squashfs
sudo mv squashfs-root edit

Bind the enviroment and chroot into it

sudo mount --bind /dev/ edit/dev
sudo chroot edit
mount -t proc none /proc
mount -t sysfs none /sys
mount -t devpts none /dev/pts
export HOME=/root
export LC_ALL=C

Edit the dns config

nano /run/systemd/resolve/stub-resolv.conf

nameserver 1.1.1.1

Install php and apache

sudo apt-get update && sudo apt-get upgrade
sudo apt-get install php

Install finnish and spanish

apt-get remove --purge language-pack-bn language-pack-bn-base language-pack-gnome-bn language-pack-gnome-bn-base language-pack-es language-pack-es-base language-pack-gnome-es language-pack-gnome-es-base language-pack-pt language-pack-pt-base language-pack-gnome-pt language-pack-gnome-pt-base language-pack-xh language-pack-xh-base language-pack-gnome-xh language-pack-gnome-xh-base language-pack-hi language-pack-hi-base language-pack-gnome-hi language-pack-gnome-hi-base language-pack-de language-pack-de-base language-pack-fr language-pack-fr-base language-pack-gnome-de language-pack-gnome-de-base language-pack-gnome-fr language-pack-gnome-fr-base firefox-locale-bn firefox-locale-de firefox-locale-es firefox-locale-pt language-pack-gnome-zh-hans language-pack-gnome-zh-hans-base language-pack-zh-hans language-pack-zh-hans-base firefox-locale-zh-hans
sed -i 's/restricted/restricted universe/' /etc/apt/sources.list
apt update
apt install gnome-getting-started-docs-fi gnome-user-docs-fi language-pack-fi language-pack-fi-base language-pack-gnome-fi language-pack-gnome-fi-base
gnome-getting-started-docs-es gnome-user-docs-es language-pack-es language-pack-es-base language-pack-gnome-es language-pack-gnome-es-base 
apt install xul-ext-mozvoikko libreoffice-l10n-fi libreoffice-voikko firefox-locale-fi libreoffice-help-fi thunderbird-locale-fi libenchant-voikko tmispell-voikko
libreoffice-l10n-es  firefox-locale-es libreoffice-help-es thunderbird-locale-es
sed -i 's/restricted universe/restricted/' /etc/apt/sources.list
apt install libreoffice-l10n-en-gb libreoffice-help-en-gb libreoffice-l10n-en-za libreoffice-help-en-us poppler-data hyphen-fi hunspell-en-ca mythes-en-au thunderbird-locale-en-gb hyphen-en-us thunderbird-locale-en-us mythes-en-us wbritish hunspell-en-za libreoffice-l10n-en-gb hunspell-en-gb

Open a new terminal to configure ubuntu preseed

sudo su
cd extract-cd 
cd preseed
nano ubuntu.seed

Ubuntu.seed contents

# Enable extras.ubuntu.com.
d-i apt-setup/extras    boolean true
# Install the Ubuntu desktop.
tasksel tasksel/first   multiselect ubuntu-desktop
# On live DVDs, don't spend huge amounts of time removing substantial
# application packages pulled in by language packs. Given that we clearly
# have the space to include them on the DVD, they're useful and we might as
# well keep them installed.
ubiquity    ubiquity/keep-installed string icedtea6-plugin openoffice.org php

Go back to the first terminal and clean up the system

apt clean
rm -rf /tmp/*
rm -rf /var/cache/apt-xapian-index/*
rm -rf /var/lib/apt/lists/*
umount /proc
umount /sys
umount /dev/pts

Exit the enviroment

exit
sudo umount edit/dev

Create the file manifest

sudo -s
chmod +w extract-cd/casper/filesystem.manifest
chroot edit dpkg-query -W --showformat='${Package} ${Version}\n' > extract-cd/casper/filesystem.manifest

Create the filesystem.squashfs

mksquashfs edit extract-cd/casper/filesystem.squashfs

Export the iso file

export output_file=ubuntu-18.04-desktop-apache-remix-amd64.iso

export IMAGE_NAME="Ubuntu 18.10"
sed -i -e "s/$IMAGE_NAME/$IMAGE_NAME (Apache Remix)/" extract-cd/README.diskdefines
sed -i -e "s/$IMAGE_NAME/$IMAGE_NAME (Apache Remix)/" extract-cd/.disk/info
cd extract-cd
rm -f md5sum.txt
(find -type f -print0 | xargs -0 md5sum | grep -v isolinux/boot.cat | sudo tee ../md5sum.txt)
mv -f ../md5sum.txt ./
# If the following is not done, causes an error in the boot menu disk check option
sed -i -e '/isolinux/d' md5sum.txt
export IMAGE_NAME="Ubuntu 18.04 apache-remix amd64"
genisoimage -r -V "$IMAGE_NAME" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e boot/grub/efi.img -no-emul-boot -o ../${output_file} .
cd ..
isohybrid --uefi ${output_file}
umount squashfs/
umount mnt/
exit

Now you have your own customized ubuntu image with anything you want to preinstall
Here's the iso files i created for this tutorial
/files

sources

1. https://bazaar.launchpad.net/~timo-jyrinki/ubuntu-fi-remix/main/view/head:/finnish-remix.sh