mazdaq

Different people have different reasons for holding physical metals. For at least some of us it is to hold value outside the system.
A spread bet is simply a bet in fiat. If you keep your bets low you can win. If you have well placed stops you can win. Most people don't do this and they eventually lose. They place too big bets, they use too much leverage. If you are successful then carry on spread betting.
With physical you can sleep at night - if the market goes mad what do you care? You are in physical and the markets are paper.
If you are successful in spread betting i think it is a good idea to keep taking profits out and getting some physical. This is outside the system. The paper price could go to zero but you can't lose your physical to the spread betting company. We saw the market gyrations in March 2020. The paper price went down to $11. There was no physical on the planet at these levels. The physical price was many dollars higher. Some of us here believe at some point the markets will break down. There is no guarantee what you will be able to get out of a spread betting account. Forget any guarantees if the markets breakdown badly.
So i would look to keep pulling profit out and converting it into UK coins. Get them out of the system instead of being held in a 'bookmaker's' account. Gold has the lowest costs to buy and sell. Sovereigns and half sovereigns are the usual recommendations. 
If you have UK gold and silver coins these are CGT free.

Don't forget:
https://www.chards.co.uk/1000-ounce-vat-free-silver-bars-switzerland/14260
together with numerous other silver, platinum, or palladium bullion products VAT free, with better / best storage rates.
@ChardsCoinandBullionDealer
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@mazdaq
Worth checking the fees for keeping positions open with your provider?
Another option to consider could be vaulted silver something like this although not something I've done myself https://www.bullionbypost.co.uk/vat-free-storage/

No!
Despite my advice about investing in precious metals: 
Gold should be your first choice, because investment gold is exempt from VAT in the UK (& also EU).
Silver is still in big demand.
For example @ChardsCoinandBullionDealer has a standing request for 30,000 silver Britannias per month from the Royal Mint, although we have only been receiving 10,000.
We did manage a few days ago to buy an extra 20,000 from a fellow distributor / competitor, but these are for offshore storage, which legally avoids VAT for larger investors.
Of course, this still fails to equal the 3.2 tonnes of silver coins we once imported from Perth Mint, back in the days of the Credit / Banking crisis. that was quite a stack, a 7 pallet load on the back of a 7.5 tonne wagon, which  I drove. (From Manchester Airport, not from Western Australia).
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