Grammar correction: 'At uni, I played in a rock band and painted' — capitalization, formality, and clarity

Corrected sentences:

• At uni, I played in a rock band and painted.
• More formal: At university, I played in a rock band and did some painting.

Brief explanation:

1. Capitalize the first word: 'At' should be uppercase.
2. 'Uni' is informal; use 'university' in formal writing.
3. The comma after the introductory phrase is optional but fine: 'At uni, ...'.
4. 'Painted' is grammatically fine, but you can add an object or rephrase for clarity (for example, 'did some painting' or 'painted pictures/painted paintings' if you want to specify what you painted).
5. An exclamation mark is acceptable if you want an excited tone; use a period for a neutral statement.