I have somewhat Unique experience here (as I'm sure at least one poster may know ). Have a look at www.libyavisa.info for a rough guide on actually getting a visa.

I remember asking the home office about UK Citizens and not requiring visas for transit: I was referred to the Libyan embassy - and I can tell you first hand that if you get any useful information from them it is either:

a) an error
b) an accident
c) designed to throw you off the scent

Alex