Well worth a visit is the Bumblebee Conservation Trust. I get so many bumblebees in the garden and they survive very happily in our long grass (I keep areas uncut so they and other insects can nest). They also seem to get on very well with the honey bees. So I was interested to find a great guide to the UK bumblebee population on this website. If you join the trust (£1 a month) you get this poster, and lots of other stuff too.