Can a bailiff enter a locked garage in a block?

No

The garage in a block, or garage en-bloc, or lock-up garage because it forms part of the domestic dwelling house.

Any domestically occupied property is protected from bailiffs entering by using reasonable force for the enforcement of unpaid traffic contravention debts,^[1] and council tax.^[2]

Bailiffs may enter domestic property using reasonable force to recover unpaid tax owed to HMRC,^[3][4][5] or an unpaid court fine.^[6]

^{[1] Paragraph 18A(1)(d) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[2] See Council tax bailiffs and entering using reasonable force
[3] See Bailiffs recovering unpaid tax to HMRC
[4] Section 127 of the Finance Act 2008
[5] Paragraph 19(2)(b) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[6] Paragraph 18(1)(b) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007}