Need some advice on palletization!

In the process of arranging my first shipment from my supplier in China direct to an amazon fulfilment centre in the UK. I'll be using AGL for the first time and a bit confused about the palletization requirements.

Supplier is currently saying no need to palletize but Amazon is not clear on the subject - some sources say they require it, some say floor loading is okay.

Has anyone been through this process and floor loading a FCL before?

Thanks.