I don't know about Public Liability insurance (is it really required) but for Professional Indemnity Insurance it will be based on turnover amongst other things.
The views expressed in this post are my own personal (HRA protected) views, and are not representative of any organisation I have any involvement with.
£47.45 up to £5,000 turnover £86.10 to to £10,000 turnover £114.00 up to £15,000 turnover £130.80 up to £20,000 turnover £147.60 up to £25,000 turnover
based on a sole trader with cover of £50,000 and no employees.
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Never buy black socks from a normal shop. They shaft you every time.
Try this site:- https://www.simplybusiness.co.uk It compares various companies for quotes. I got a quote from Glemham for £84 for £50,000 cover with no employees and turnover of £25,000 or less.
I was just researching PII at the time. I haven't taken any out yet as I'm not yet a member in practice. It will probably have gone up considerably by the time I do !