The UK Standard Route Document suggests routes into UK airports from the NAT exit points. Generally, more than one route is available with one chosen by the airline concerned.
Looking at last night's flights, virtually all airlines chose Track X with exit point DOGAL. From there, they all flew:
DOGAL DCT BEXET DCT BAKUR UN546 STU UP2 OKESI Y3 BEDEK OCK2F STAR.
Equally, they could have (but no airline did) have gone:
DOGAL DCT BEXET DCT LIFFY UL975 WAL DCT NUGRA BNN1B STAR.
The Standard Route Document similarly suggests routes from DOGAL to EGGW and EGSS. The suggestions for both airports are identical. They are almost exactly the same as the EGLL with the STAR designator nearly the only difference. OCK2F is replaced by LOREL2S and BNN1B is replaced by WAL LOREL 4F.
To summarise, route inbound to airport depends on choice of NA Track and airline choice of route from Standard Route Document (although these are not compulsory and other valid routes will be accepted by the flight planning system.
SFS