Annual accounts and the Company Tax Return are related, but each is a separate filing. The accounts go to Companies House and the Company Tax Return (CT600) goes to HMRC. Filing either one does not pay your Corporation Tax. Payment is a separate step.
Your first accounts commonly run from incorporation to the accounting reference date, and that period can be longer than a year. A Corporation Tax accounting period cannot be longer than 12 months, so a long first accounts period can need two Company Tax Returns.
A company is a micro-entity if it meets any 2 of: turnover £1 million or less, £500,000 or less on its balance sheet, 10 employees or less. It can send just a simpler balance sheet to Companies House, but HMRC still gets the full statutory accounts.
No bookkeeping needed first. Bank statements are enough to start. We do the bookkeeping, prepare your accounts and tell you if anything important is missing.