If you take a loan to spend, but do not spend the coins, you get tax deduction for the interest cost
If you take coins to another country and spend there, you will be very welcome since you are the rich foreign investors for that country
So the most common practice will be: Earn a lots of coins at home, and go to a foreign country and retire
I assume johnyj means you move to another country for the whole tax year (or the rest of your live), in which case IIUC you wouldn't owe UK Capital Gains Tax for that tax year.
If the idea is that you'd just go overseas to shop then come right back while remaining a UK resident the whole time then surrenduring your UK passport probably wouldn't help either.