Looks like the current advice is to phone your local authority. Hopefully they a have a collection service at a local dump. Certainly do not put them in the bin - Cadmium is not nice stuff to put into the environment.

According to Q12 here:
http://www.defra.gov.uk/Environment/waste/topics/batteries/batteries-faqs.htmhttp://www.defra.gov.uk/Environment/...eries-faqs.htm
all NiCads collected in the UK are exported to France for recycling...