Your staff will be handling these products which may contain substances hazardous to health. It may be a good idea to carry out a COSHH assessment for these products. This will give you an idea of the mixtures, significant health warnings or risk labels. Plus the control measures such as spillage, storage, handling, disposal etc.

The engineering controls should also help you control associated hazard/risk better. As your staff is selling this in a charity shop, they probably won't interact with the substances as a user. They will just pick up from shelves, pass to customers, in the sale process. 

Your risk assessment should also highlight this activity and I would suggest provide your staff with information, instruction, supervision and training on what to do in event of a spillage for instance.

I can only give you areverse answer.  My partner has a hand sprayer certificate having completed a course (can't recall the full details) and does have to show it to buy certain chemicals. The point being that a short while ago I could buy them across the counter without a certificate and now I can't, as the purchaser is required to shop some form of training or has been added to their register.  I worked with a farming company and about 3 years ago, even the main sprayer operator who relied on grandfathers rights had to become qualified.   My input to the OP might be that in the absence of finding clear answers, might be to check the local garden shop  or a well known online seller, and if they don't sell it, then you don't sell it either.  

Edited by user 27 March 2019 15:55:46(UTC)  | Reason: Not specified

For the nature of your business these "gifts in kind" are people dumping waste for your disposal.

I appreciate this sounds harsh but at the end of the day the REACH regulations have been around since 2006 and as a new approach directive determine a lot of duties for those who "place a product to market" - a charity shop would be considered a distributor in the supply chain so you have responsibilities for the information provided by either label or Safety Data Sheet to your customers even where you have not prepared this yourself.

Another consideration is that for the UK next year (already in place in several EU member states) consumer facing products require registration with a national poisons centre (Safety Data Sheet and declaration of constituents) supported by a Unique Formula Identifier (UFI) on the packaging.

"Old" packaging is unlikely to carry a UFI and may bear the previous square orange pictograms and hazard classification which have been illegal in the supply chain since 1st June 2017.

Then you have to consider ancillary legislation such as Explosive Precursor and Poisons, Psychoactive Substances..... it really isn't worth the hassle.

Clearer advice for retail can be found at https://www.businesscompanion.info/ where they give guidance around various legislative acts e.g. the sale of butane to under 18's is from the Anti-Social Behaviour Act