Hi Mark Taylor,
I would refer you to:
CA22100 - Plant and Machinery Allowances (PMA): buildings and structures: caravans,
You can only claim PMA if the hut is located on a holiday caravan site registered as such by the local authority under CSCDA 1960.
It’s not clear from the information that you have if this is the case.
This forum is for questions of a more general nature where we can provide specific links to guidance for customers themselves to make an informed decision.
As your original question is very specific you must write in for us to provide a more definitive answer.
Address can be found here:
Self Assessment: general enquiries
Thank you.