Is Business mentoring/coaching tax deductible?

Marcusian

I am an online diet and fitness coach and turnover about £30k a year (i am 13 months in). I would like to invest in some business mentoring, from someone who offers this is as a service, directly for coaches like myself and my industry. Is this tax deductible? It's not about gaining a new skill, it's about growing my business within the market it already exists in. My understanding is that it would be? I would of course have all the necessary invoices etc. 
EDIT
I am a sole trader. 

Jeremy535897

The official line is here:
https://www.gov.uk/hmrc-internal-manuals/business-income-manual/bim35660