I am trying to create a Condition where the mask allows entry £'s and pence so £####.pp

Please change the Number field into a short text entry field. And make sure you use the # symbol to map numbers, not * as specified in your condition, here's an example condition I have set for you:

I have cloned your form and created the condition for you, here's my cloned version of your form:

https://form.jotform.com/71633580031953

Here's how to clone a form into your account:

How-to-Clone-an-Existing-Form-from-a-URL

Also, please refer to this guide for more information on how to set a mask:

How-to-Set-Content-Mask-on-a-Form-Field-Based-on-Another-Field-Input