Depending on where you are in the country, OP, it might be useful to know about some of the bigger greyhound events. This weekend, on Sunday is the Great Greyhound Extravaganza in Newmarket - fabulous shopping and gorgeous pointies as far as the eye can see. Most of the rescues from the SE have a stall there, and these sorts of events are incredibly social and friendly, with everyone having picnics, chatting to friends etc.
Later in the summer will be the Northern Greyhound Gathering, there's a Scottish one, and in October there's the Great Greyhound Gathering at Stoneleigh in Warwickshire.
Other smaller events are held during the summer by individual rescues and I'd also strongly recommend the Great Global Greyhound Walk, which is a fab event and has walks going on all over the country, all free, all fun and again very sociable indeed.
Once your hound arrives, you'll find there's an amazing network/subculture of other pointy owners - most rescues usually have a full programme of playdates, walks, picnics, events, shows etc. and you rapidly find that your dog has a better social life and more expensive wardrobe than you do. 
Do take advantage of these - greyhounds are very social with other greys, it's a massive change for them when they go to be a lone pet after a lifetime spent constantly with other greys so they really appreciate these sorts of events. You'll also find lots of friends and quite often things like recommendations for good greyhound savvy local vets, safe places to exercise off lead, and dog sitting partners (incredibly useful if you need to go away for a night and so lovely to see your hound enjoying a sleepover with their buddies).