What Details Do I Need to Keep for Tax Returns for Arbitrage Trading (UK)?

I’ve just started doing some arbitrage trading using a couple of online cryptocurrency exchanges, but I’m not sure what details I need to keep for the tax man.

Do I need to keep a record of all my activities? Say

• sent £10,000 from bank account to exchange one;
• bought 113 coins for £9,124;
• sent 113 coins from exchange one to exchange two, with a fee of 0.1 coin;
• sold 112.9 coins on exchange two for £10,124;
• withdrew £10,124 from exchange two to bank account;
• sent £10,000 from bank account to exchange one;
• etc, etc.

I would have a bank account designated to doing this trading, so there wouldn’t be overlap with other activities. As such, alternatively, can I just record/provide

• the money in my account at the start of the tax year;
• money in my account at the end of the tax year;
• bank statements showing money entering/leaving the account;
• exchange statements showing money arriving/leaving exchanges.

As mentioned in the title, I’m in the UK.