In general, the UK concept sounds just like Australia. Regarding property CGT, if you buy a property 10 years ago for $5m, the day you arrive in Australia it's valued at $10m, then you sell 2 years after arriving in Australia for $12m, then the CGT you have to pay is only on $2m (the difference between the current selling price and the value at the time you became Aussie resident again). I am not sure if the UK is same concept as this.
The thing I am not sure about is how do you prove the value of your property on the day you became a resident again. I moved to Australia on January 11th this year. I just took a screenshot of the property value from HSBC and Standard Chartered online valuation tool on this date. I am not sure in the future, when I sell my HK property, if the Aussie tax office will accept this kind of website proof of valuation. We'll see. No intention of selling just yet.
Regarding moving money from HK to UK, I don't think there is any kind of tax on this if the source of funds is just HK savings. ie you held the funds in a HK bank account, then moved it to UK. This should be tax free. But if you sell a property in HK, then move these funds from sale of property from HK to UK, then this is where you should pay some kind of tax, in this case CGT. So you may need to provide proof of the source of funds when transferring.
Similar with other investments, shares, etc. If you hold a pile of HK shares, transfer the money to UK, then I expect if you made a profit between buying and selling the shares you have to pay GST tax on this profit.
But it works both ways. If you are a shit investor and bought HSBC shares for $60, sold them for $40, transfer the money to UK, then you made a LOSS and this will reduce your tax in UK right? I mean you can claim a deduction from UK tax office at end of year from the loss you made on your HK investments. Anyway this is the way it works in Aus. All your worldwide income and losses is considered in your tax payable.