It seems to suggest that buying bitcoin based on speculation is considered gambling and thus GCT isn't applicable (nor is offsetting your losses against other taxable income).
"Gains and losses incurred on Bitcoin or other cryptocurrencies are chargeable or allowable for CGT if they accrue to an individual [...]"
But also:
"depending on the facts, a transaction may be so highly speculative that it is not taxable or any losses relievable"
In my opinion, this means that gains from regular buying and selling of bitcoin are very likely subject to CGT, and that there would have to be an additional element of risk or chance to make it more speculative in order to be exempt from CGT.
I wouldn't want to defend any other position and therefore I will be including my bitcoin gains (and potentially losses) in my CGT tax return.