From time to time we include 1 or 2 tins of glue/ adhesive with our product when despatching our goods to our UK based customers.
Because of the small quantities, can anybody tell me if this falls under the carriage of dangerous goods regulations?

We've always sent glue and adhesive out with our products, either 2 spray cans of adhesive 500ml per can, or 2 tins of liquid adhesive, again 500ml per tin, with 2 tins of hardener 250 ml per tin.
Never had a problem when we've sent it as part of a consignment, but that's probably because we haven't declared it.
The issue arose recently when we tried to send glue as a stand alone item and 2 of our carriers refused to take it.
To there credit they asked us questions about how we normally dispatch this product and we told them, as part of a consignment.
Both carriers reckon we need to be assessed, certified, and audited as a dangerous goods supplier, which for us is a bit extreme as we only ever dispatch low volumes of the product.
When sending as part of a consignment, should we label the crates accordingly with the relevant documentation (dangerous goods notes) and stickers?
My view is if this is the case its more trouble than its worth and we will probably inform our customers they have to source this product themselves.

The first place you should look is on your Safety Data Sheet under section 14, the transport information.

That will state whether or not these materials are classified.

If they are classified, the chances are they will be easily dealt with by any competent DGSA.