Stock and WIP valuation with my labour input

I'm a sole trader / self assessment tax person. The problem I'm having is my reading of the rules doesn't allow for me to include my labour into the value of parts or unfinished (or finished) assemblies. I can handle that for the purpose of my tax return but it doesn't sit right with me, so I want to check that I will be doing the numbers right. Lower of Cost and NRV. The cost will be the lower value. Cost: includes raw materials, direct and overhead costs. My 'problem' is that my labour isn't a direct cost. So this throws up anomalies in my mind such as two identical parts on the shelf will have very different stock values depending on whether I made it myself or paid some else to make it. For a finished product that will be sold for £3000, the costs in it might be £500. It seems wrong to value it at £500 in my tax accounts. It will be valued at £3000 in my "management accounts". Looking for confirmation that my reading is correct, and I ignore my labour. Or a basis for including my labour on the value. Thanks.

Hi,
Your own labour can not be claimed as an expenses against your self employment profits for Income Tax purposes.  
The value of the asset at the end of the production does not have an impact on the overall profits reportable on your return and only on your balance sheet. When the product is sold the sale value should be included as trading profits.  
You can see guidance for valuing stock for balance sheet purposes here:
BIM33135 - Stock: valuation: lower of cost and net realisable value: cost
Thank you.