I am planning to enter Libya on or around the 14th March. Which may be too late for you, although there may be ways around that.
I have been in contact with Naziha at United Travel (0207 258 1413), their number was given to me by the Libyan Embassy.
They will organise the visa for you within a week, including a 'guide' at the border, but at a cost of £170.
I still have to get other visas as well, so in the interests of time and ease, I will be using them for my Libyan visa.
Whatever you decide, let me know how you get on.