We cannot advise on the matter of funding.
We cannot provide a definitive answer as, under self-assessment principles, HMRC does not generally provide clearance on how individuals should declare their income or gains.
It is instead the customer's responsibility to assess the available guidance and arrive at their own considered conclusions.
It might however help if I confirm that HMRC generally takes the view that the act of buying and selling forex etc will normally fall short of trading and would therefore be subject to Capital Gains Tax.
There is guidance available in the Business Income Manual, from reference BIM56800 that should allow you to assess your position and declare your income and gains accordingly.
BIM56800 - Financial traders - instruments and shares: contents