Yes, I've been ... it's less than pleasant, but you'll probabaly meet some interesting folks there, who are fighting for the right to stay in the UK and fearing deportation to danger back home - I found it quite a sobering experience.
Anyway, yes, get the train - Lunar House is signposted from East Croydon station and it's a 5/10 minute walk.
If you are in need of a celebration or comiseration drink afterwards, head into the town centre, there are loads of shops and cafes etc ....