Lazygardener - that's sad about your house martins. Why not try luring them back by making them a bespoke nesting box (http://www.gardenersworld.com/how-to/projects/make-a-house-martin-nest/) or leaving a muddy area for them to build their own in spring? Or both... Re your unidentified insects, are you sure they're not bumblebees? You could ask Richard Jones, or email us a photo (see our Contact us page).
ziggyblackjayne and Ryan - the fact that ants are nesting in your compost bin means your compost is too dry. If you don't mind the ants the leave them be, but the usual trick is to water the compost heap - the ants move on and your heap breaks down quicker as it's moist. Dry heaps are also favoured by rodents...
daisy rose - leave a comment on one of Richard Jones's blogs, I'm sure he'll know what it is.
Brenda - I'm sure your ants won't be harming the garden, they'll be part of the natural balance. Could you try to attract birds into the garden by feeding them?
Kate