Submitting a new page to Google
If you are adding pages to your website you probably want Google to index them as soon as possible. If you wait until Googlebot finds the page, even if you do have the page listed in your sitemap, then, depending on how popular your site is in the first place, you may have to wait a long time. Even then, just because you submit the page using Search Console it may take some time to be found.
As always, the page must have unique content, and something that an Internet user might be searching for. This page, for instance, is unlikley to be found by a search as it only contains terms and concepts that are availble elsewhere on far more popular/important websites.
When uploading a new page or pages, pay attention to the fact that you may have a quota of pages that you can submit to Google.
Add to the sitemap first
While this sounds obvious I have observered that if I submit a new page for indexing at the same time as the updated sitemap it is both unlikely to be crawled by Googlebot but it won't be indexed. Submitting the sitemap with the new page can be see being aceessed in your server logs and Google Search Console will tell you when you sitemap was last accessed. There is no point in requesting indexing unless the sitemap has been read.
Requesting page indexing
Search Console allows you to request a page be idexed but it seems to need the www subdomain:
https://www.tempusfugit.me.uk/submitting_new_page_to_google.html
Make sure you get the process order correct
Too often I have requested a re-index before I have uploaded the page. This applies to edited and updated pages as you can't inspect and test new pages unless they are on the server.
I am not sure what the consequences of requesting re-index too soon. I am concerned that it may trigger a penalty if a 2nd request is made too soon.
It is strange that this page fails validation, using icon in footer - - this is for the index page. nu does not like the file name??????
A page with _1 after the google validates just fine.