(Seeing that you're in the UK...) reading CAP371 usually helps people to get to sleep.
On a serious note, try some lavendar oil under the pillow. Some people say that warm milk helps them to sleep, although I haven't tried it because I hate milk. Camomile tea is supposed to be good too (it's caffeine free, by the way).
One of the tricks is to try to stay awake. That is far more effective for putting one to sleep than to try to go to sleep.
There's also "that" horizontal activity - it does help with sleeping.