Hi ​@Bradders6 

From my understanding, an Esim used with an iPad is on a data only plan and therefore won’t have a ‘phone number’ as such. 
Try…. Settings > General > About and scroll down to the "Physical SIM" or "ESIM" section to find the ICCID associated with your data plan.  
An Integrated Circuit Card ID (ICCID) is a unique, 18-22 digit serial number stored in a SIM card’s memory that identifies it and acts as a physical or digital (eSIM) signature, identifying the SIM card itself (not the user or device). It is essential for activating services, switching carriers, and tracking SIMs in networks.

The other option is to contact the Live Chat to discuss this:-
(Having the ICCID number may help in setting up your account)

 https://www.idmobile.co.uk/live-chat

When you contact the Live Chat :-

Type ‘talk to a person’ in the dialogue box and this will bypass the unhelpful chatbot. 

Please be patient as the agents handle a few conversations at any one time so there will be a delay in connecting with an available agent and also any replies to your query.

Good luck x

Hi ​@Bradders6,

I've just sent you a private message to help get this sorted.

To find it, click your profile picture in the top-right corner and select ‘Private Messages’.

You can also use this direct link to your inbox: https://community.idmobile.co.uk/inbox/overview

I'll speak to you there.

Thanks.

Kwanele

The iD Mobile Team

Thank you both

I got an email today with the number. 

Hi ​@Bradders6,

Thank you for letting us know, and glad to hear that you have come right. 

If you need any further assistance, please do not hesitate to reach out again. 

Regards,

Gemma M

The iD Mobile Social Media Team

My new problem is that now I've entered the number, iD are trying to send a text to my iPad to verify, which I obviously can't receive. Any ideas? This can't be the 1st time somebody has used an iD SIM in an iPad 

Hi ​@Bradders6,

Thank you for getting in touch. 

I am sorry about that however as iPads are unable to receive SMS messages, the verification text for your iD Mobile number cannot be delivered directly to the device. To complete the verification process, the eSIM must first be installed on a mobile handset that can receive texts. The verification code is only sent via SMS to the iD Mobile number and cannot be delivered through any other method.

-Anneline

Thank you for responding. The email with the QR code for the eSIM made it clear that it can only be used once. If I did that then surely I couldn't add it back to my iPad.