It's been a struggle to find one specifically for warehousing. But well done you for thinking about it! One manufacturing site I know are using a catering course. When I pointed out how irrelevant this was they just shrugged.
I found a retail course which I'm wondering if that might at least in part have some overlap: Level 2 Online Food Hygiene Training Course | For Retail
And another one: Food Safety for Retail | Level 2 | Qualification
The other option is designing it yourself or asking a training body or consultant to design something bespoke. It might not cost as much as you think. But there is a perception you need an externally certified Level 2 course for your staff for BRCGS, you don't. You just need a course which covers the food safety requirements and making that bespoke to your facility is actually really well looked upon by most auditors I've found. You just need to make sure you have the team resources to train it when needed.
So if you need a quick fix in the short term, the retailer training might "do" but longer term I'd write your own or get it written for you.