What renovation work can't legally be undertaken without the certs?

[drummergirl34]

If I wanted to do some minor renovation - new bathroom / kitchen shelves / worktops etc, what work do I need legally qualified people to do? Is it just installing a cooker if gas, and any plumbing works? Things like installing a bath / sink etc would be fine if just connecting to existing plumbing?

The only thing you have listed, which needs someone who is Gas Safe registered, is connecting a gas cooker. None of the rest of it requires any specific qualifications or certification, although do make sure anyone you contract to do the work is capable of doing a good quality, competent job.

Plus if anything requires structural alterations eg removing or building a new wall or staircase you will need building regs signoff.