LGW Airport Lounge (LoungeKey HSBC Premier)
 

Has anyone accessed the lounges at Gatwick airport using LoungeKey?

It's included with HSBC Premier account (I think there may be a cost per person, £15 each?) but not sure if a) worth it (family of 4) or b) how easy to use/access (book in advance or pay on the day?).

Thanks