Rewrite all urls with .html extension except for index.html - apache

Question

The following htaccess is removing the .html extension from our files fine eg:
/page1.html redirects to /page1
but we now cannot add folders as it is redirecting the /new-folder/index.html file to /new-folder/index
Is there any way around this?
RewriteEngine On
RewriteCond %{HTTPS} off [OR]
RewriteCond %{HTTP_HOST} !^www\.website\.co.uk$ [NC]
RewriteRule ^(.*)$ https://www.website.co.uk/$1 [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^(.+)$ $1.html [L,QSA]
RewriteRule ^([^\.]+)$ $1.php [NC,L]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*\.html\ HTTP/
RewriteRule ^(.*)\.html$ /$1 [R=301,L]

Answer 1

Change you 301 rule that removes .html to this:
RewriteCond %{THE_REQUEST} \s/+(.*?/)?(?:index|(\S+?))\.html[/\s?] [NC]
RewriteRule ^ /%1%2 [R=301,L,NE]
# rewrite to dir/index.html if it exists
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+)/$ $1/index.html [L]
This will redirect /new-folder/index.html to /new-folder/ but will redirect /new-folder/form.html to /new-folder/form.