Matt,
as one who 'worked' that bit of airspace for many years, there was a requirement to inform LLC traffic to "Keep a sharp lookout, there may be traffic in the Low Level Route, unknown to ATC".
As the original EGCC/EGGP Zone was so wide, the LLR was introduced to allow VFR a/c to transit north/south, clear of the high ground of The Pennines and the requirement to operate single-engine,over water, west of Wallasey.
Many pilots thought there was a requirement for ATC clearance to use the airspace, but, due to the 1250ft restriction being at the base of radar cover, this was not the case. In the past, DC3s and C130s have used the LLC, without a word to ATC.
Have fun!