Depending on how you intially configured your SD card with PiBakery, you may see some blocks appear in your workspace. These blocks will be under the On Every Boot hat, and will only appear if you initally used the On Every Boot block when customising your SD card.
You may also see the On First Boot block. However, this will only appear if you have never booted your SD card in a Raspberry Pi, because as soon as you boot the SD card, these blocks will be run, and therefore cannot be edited by PiBakery any longer.
In short, you'll only see blocks in your workspace that you can edit. If you don't see any blocks in your workspace, that's fine too - you can still add some more!