DNS management - Do the Configure, Add records and Submit buttons do anything?

[#1]

I have been 'migrated' from a good old Force9 account (happily with them for 20 years!) to a PlusNet account.

This was 'pushed' upon me because, after initially, upgrading my Force9 broadband plan to Unlimited Fibre Extra in March 2020 (which I got after a few days), after some time, I was told the 'billing system' could not handle the fact that I was a Force9 customer and paying for Unlimited Fibre Extra (don't ask me why?).

Starting in October, after one unsuccessful attempt and now a partially successful attempt (over many weeks) to 'migrate' my account, I find I still have my 2 domain names registered and hosted under my new PlusNet account, but I no longer have any webspace or have access to my CGI webspace (both were explicitly stated conditions of the transfer). Also email (with all my mailboxes and aliases) was not 'migrated'. After a week long struggle (without any email) and daily phone calls, PlusNet managed to get my domains to point to my new account mailbox.

As a result of having two domains with a status of 'Registered and Hosted' by PlusNet, but no longer being hosted by PlusNet for webspace, I wish to point the domain names to a webhosting company (I have already started the subscription and have their webserver IP addresses and mailserver names for reference).

My question to the forum is, does the DNS management 'Configure', 'Add' and 'submit' buttons do anything, and if they do, how long should I expect to wait before the records are invoked and DNS propagation takes place?

The records I have entered for one of my domain names (trialling one first) are:

mydomainname.co.uk.             A            111.111.111.111
www.mydomainname.co.uk.    A            111.111.111.111
                                                MX   5     mx1.newwebhost.co.uk.
                                                MX 10     mx2.newwebhost.co.uk.

In the Configuration options, I have checked 'Other' in both the 'email settings' and 'domain hosting settings'.
I note the use of full stops after the left field in the A records and after the right field in the MX records.

I 'submitted' these records on the evening of the 14th December. So far, an 'nslookup' still points to the PlusNet servers.
Can I expect this to work and how soon? Or should I just request a complete 'transfer out' of my domain names instead?

Any advice would be welcome. Thank you.

[#2]

Postscript to the above:

After trial and error and reading conflicting descriptions of what is required in the left field of an A record, I think the following has worked for configuring mydomainname.co.uk to point to my new webhosts' name servers in the PlusNet domain configuration panel:

www            A     111.111.111.111

(where 111...... is the Ip address of the webhosts nameserver)

No suffix of a full stop was used on 'www'

This appears to work for http://www.mydomainname.co.uk

Now I am adding

.                A      111.111.111.111

(where there is a '.' in the left field) to  point to the webhost nameserver for http://mydomainname.co.uk

I will update this post with my findings again

Merry Christmas

David.

[#3]

I think this works:

www                                    A                111.111.111.111

mydomainname.co.uk.        A                111.111.111.111

                                             MX    5       mx1.newwebhostmailserver.co.uk.

                                             MX    10     mx2.newwebhostmailserver.co.uk.

( where 111.111.111.111 is the IP of your domain webspace in your target newwebhost

and the MX FQDN is followed by a '.'  as is mydomainname.co.uk in the left field of the A record)