Is it JUST their headquarters or can you use it like a normal high street branch ? Seems like the closest one to me, and I need to transfer cash at one ASAP.
Walk to Waitrose, facing Waitrose there is a walkway to your left walk through there and you walk over a bridge/escaltor and end up in another building (they all look the same) you shall then see a Starbucks coffee stall and to your left there is a Barclays.