The UK needs me!
In the end you have to decide before God where you should be, but make sure you realise:
There are a lot more Christians in the UK than in, say North Africa. Doesn't seem fair, really, does it?
You need a call from God to remain at home just as much as you need one to go to *??*
You might have considerable influence on your local church if you did work in another culture, and begin to look at things from a different perspective.
Think what you could learn as well as give from a time working abroad.
P.S. Crosslinks has people in the UK as well...