Updating post from Reddit.
Can I claim both the property and trading allowances or do you just get one or the other?
Yes.
https://www.gov.uk/guidance/tax-free-allowances-on-property-and-trading-income
“You can get up to £1,000 each tax year in tax-free allowances for property or trading income from 6 April 2017. If you have both types of income, you’ll get a £1,000 allowance for each.”
Assuming you have property income AND income from trading.
Not both against the rental income