The pit lane entry means going straight on at Vale. The tarmac for it was down before last years F1 event.
I belive this new pit lane will be used for anything using that part of the track. If BTCC decides to use the half of the track that uses the new pits then they will.
Also, as with the Abu Dhabi track, Silverstone can now be split into 2 fully independent circuits which can be used at the same time.