You're starting travel from lhr, so it going to infer that you're talking to CTOs with British accents.
Stop.
like others have said, LIC clears you to self procure. Talk to Finance when you file the voucher. If you want defense in depth, put in the remarks (you're probably doing your own orders in DTS) that self procurement and LIC are approved per your commander.
Just be sure and book on an American flagged carrier. I've seen dudes get refused reimbursement when they booked on Virgin, etc. City pairs are your friend, and back me up with the JTR. I left the Heath about 3 years ago.