I think the current deal is "subject to unit capacity". File the SRD route but as soon as you can after crossing the FIR boundary ask London Control if you can take the short cut. As WWW says, if 323 is active then you have no hope. If it isn't, well it then depends upon whether London Mil have the capacity to take you. Of course, your company may have a view upon you flying through bandit country - that isn't any of our buisiness.