Hi Zu Ko,
Pre-trading expenses are expenses that you incur before you start your business.
You can claim them as tax-deductible if they meet the following conditions:
The expenses were incurred within seven years of you starting to trade.
The expenses would have been tax-deductible if you had incurred them while you were trading
You treat them as if they were incurred on your first day of trading.
You have receipts and paperwork to support the claim. Further guidance is here:
Expenses if you're self-employed