Cheapest way keep Email Access

VM only allow you to keep an email address if you remain a Broadband customer. So if you want to keep the address you have no option but to retain one of the Broadband packages. If you cease to be a customer the email account is closed after 90 days.

Just drop your speed then use VM as a backup ISP if your looking for another ISP

Make sure you have an offline backup of your contacts and important emailed data. It is not safe to rely on email as a permanent filing cabinet, as some have recently found to their cost. 

Whatever you decide to do you need to make a start on migrating your VM email accounts to a portable provider like Gmail/Outlook /Proton etc. VM has clearly indicated that it is winding up its email provision in due course. In addition migrating email accounts will take longer than you think. 

DreederUK​ 

"have grown quite attached to my ntlworld email address, I mainly use mobile browsing and dont need broadband at home, but, I need to retain access to the email account...  "

Once you close your VM broadband account you will only have 90 days before VM closes your email account.  Here's VM's explanation about that 

https://community.virginmedia.com/blog/Digital-life/some-important-information-if-you-have-a-virgin-media-email-account/5607207

So if you are absolutely adamant that you want to keep your Ntlworld email account then you are stuck with having to pay for a VM broadband account. 

However, even if you do stick with VM, the future of your Ntlworld email account is not completely guaranteed. 

Since 2022, VM has no longer provided  VM mail accounts to new broadband customers. So, as Cardiffman282​ has already intimated, the future of the VM email service is unclear at best because the number of live VM email accounts is reducing all the time.

The good news for you is that if you only use mobile data  and  don't need broadband there are a number of email services that offer free email accounts. See here for some ideas   

https://www.lifewire.com/best-free-email-accounts-1356641

All those free email accounts will work on any mobile broadband service and you would be much better off moving to one of them.

Coenoby

If you have an iPhone or iPad you get a free email address from Apple.

DreederUK​,

Do heed the good advice already given and migrate away from Virgin Media's basic email service to another offering better security and features; the effort invested now in doing so will undoubtedly be less than that when events force the move in future.

FWIW the cost of a broadband only service for 18 or 24 month is equivalent to several or more years of a good paid for email service.