What you really want to do is: into the last section of woods before spooky woods, look for the track that turns left, take it then turn left at the next track follow that up and over the hill, then at the bit where you meet the spooky wood climb coming out onto the fireroad take the singletrack that goes along the wall. Follow that down to the bottom, hook up with the black and take that all the way to the mast, turn left at the mast, follow the track, turn right at the junction, follow that down to the road, up and over the road onto the open hillside opposite, up onto the ridge turn right then look for the old trails that go from the concrete reservoir thing. Follow those down the obvious ridges and old dh trails into innerleithen. do a lap of inners, but instead of finishing at the normal place in the carpark, climb back up to the hut, go down the SUW (taking note of the beautiful trail on the otherside of the valley), at the bottom of the SUW turn left and head along the road for a mile or so until you see an obvious path heading up to the right (the one you saw earlier) head up there, turn right at the top and follow that until it gets you to the top of gypsy glen. Down gypsy glen and back to GT via janets brae.
Epic route and I’d challenge you to find a better one anywhere.