HMRC Admin 10 Response

Hi
You need to check what value of the items was declared on the individual packages. Use form BOR286 if you believe the Customs Duty or import VAT was wrongly calculated on an item you imported by post using Royal Mail or Parcelforce.
Report incorrect Customs Duty or VAT on items imported by post (BOR286)

HI
Please see the guidance here: Tax if you leave the UK to live abroad

HI
If you have an online tax account you may be eligible to use the 'realtime' Capital Gains Tax Service: Report and pay your Capital Gains Tax

Hi
You can tell HMRC online: Stop being self-employed

Hi,
We are unable to check individual tax records through this forum,  if you have not received a reply you should contact HMRC: Self Assessment: general enquiries

Hi
If the £18,000 acquistion cost was for all of the shares you bought, then you would need to apply the relevant proportion to the shares you are selling. 
In this example if you paid £8000 for shares that you are selling for £16,000 your gain would be £8000. After the annual Capital Gains tax-free allowance of £3000 (assuming you have not sold or disposed of any other assets within the financial year), CGT would be due on £5000. 
As you are not disposing of, or selling the shares that you are placing into an ISA no CGT is due. If you choose to sell or dispose of them in the furture you may need to pay CGT then - depending their value at the time. 
More information can be found here: Capital Gains Tax: what you pay it on, rates and allowances

Hi
You can work out entitlement (the proportion of your gain you get relief on) to Private Residence Relief when selling your home here: Work out tax relief when you sell your home