Need a letter from solicitor as proof of sole trader business

I am a sole trader based in the UK trying to verify a Google Play developer account, which has been set up as an 'organization' type account.

The developer account type was originally a personal account. I then requested to change to this after consulting with Play support who said this was ok as long as I had a DUNS number.

I got my DUNS number and the account type was changed to 'Organisation' by Google.

Now when trying to start the account verification it says you need to provide:
- Certificate of incorporation
- VAT registration certificate
- Certificate of registration of charity

The problem is sole traders in the UK do not have any of these as they are not limited registered companies (ltd). I am not registered for VAT and dont have a business bank account in the same name as the developer name.

So their support has said you can try and provide other documents or contact the UK government to provide appropriate proofs (which in itself is not very helpful as it is them that will ultimately decide what is acceptable to them)

So I have read that a letter of statment from a solicitor or accountant could be appropriate proof, which is what I am looking for asap, based on the following particulars:
- The solicitor's or accountant's official letterhead
- Date of issuance
- Addressed "To Whom It May Concern" or specifically to Google if required
- A clear statement confirming my status as a sole trader, such as:
"This letter is to confirm that [My Full Name] is operating as a sole trader business in the United Kingdom, trading under the name 'Some Business Name'."
- My business details:
- My full name
- My trading name (which would be the same as the developer name on Google)
- My business address
- My Unique Taxpayer Reference (UTR) number
- The date I started trading
- A brief description of my business activities
- Confirmation that I am registered for self-assessment with HMRC

The solicitor's or accountant's signature, printed name, and professional credentials.