A minor change, such as updating the bibliography/booklist for a module, does not require formal approval (but please tell the Library!). A major change, such as changing the assessment methods for a module, will normally need approval from the relevant committee within your department. Further guidance as to what constitutes a major or minor change can be found in the Guidance on Approval of Module Proposals for Academic Departments
Changes to collaborative modules will still need approval through the relevant Faculty Committees. This would include changes to staff from other institutions teaching on the module for whom CVs would need to be approved.