Commodity Code for Desktop PC

Hello, In June 2017 when I was shifting to the UK from Middle-east, I brought my PC in a big cardboard box, I was charged with no tax or no duty at all on Airport. After some years I thought it’s a good time to buy a PC I ordered a PC from the US via Forwarding Services, now my PC has arrived in the UK I’m being charged with some sort of tax, as the PC 100% for personal use paid via my personal debit card to my home address. Value of the asset is a total of $2155.70 with Shipping fees and insurance. (it’s in USD) I believe it shouldn’t charge me tax as before in 2017 they didn’t, I am very confused. My Tax invoice hasn’t billed me yet it is due in 2-3 days of 6th May which I will receive via post.

FYI: It’s my first time for receiving anything from US to UK via a forwarding company, I do usually buy stuff from Amazon US which delivers to the UK, the order was placed on Amazon (US) to Forwarding Company’s Address (US) and they shipped to the UK to my Address (UK), I thought it would be a normal delivery as I do usually every day online. I had no idea I will be charged with more tax.
The package was shipped from a tax-free state in the US.
Could anyone tell me how much tax will be charged on the Asset? As value described above.

What if the package was shipped with tax from the US, will the case be different?