I use a 2 man tent from Mountain Hardware (Drifter 2) that packs down nice and small and a sleeping bag (mummy style) for summer that does as well. I use a self inflating sleep pad by Therma Rest that has been doing it's job for years now. I recently bought a self inflating pillow that makes camping much more comfortable for about $10.
Generally speaking buy a sleeping bag rated for 20 degrees cooler than what you actually expect to normally use it for. I have a Summer bag and a Spring & Fall bag that is incredibly warm down to -20C. But then I camp a lot!
It all fits in a 25L dry-bag by Outdoor Research that I attach with a 1" (by 8')ratchet strap.
Don't cheap out on the tent or bag, unless you want to be packing heavy and being miserable if the weather craps out.
Other tips from an experienced camper: Don't pack cotton jeans or shirts they take up too much space and are heavy, this is especially true for items like towels. A couple of micro fiber cloths from the automotive store work just as well for drying you off and dry fast and pack light. A pair of hiking pants (that the legs zip off) save packing pants and shorts and save space and weight.
Pack some light weight shoes for after the days ride. I use rafting shoes since they are extremely light and pack much flatter than runners. They still look OK if you want to go into a restaurant or the like vs say "flip-flops". Pack something like a micro-fleece sweater instead of a cotton hoodie since they are so much lighter and easier to pack. If it is a cool evening around the camp fire you can always use your bike jacket to stay warm.
Finally don't forget your rain gear, and keep them easy to get to.
I have a Hennessy and love it! Super compact light and servers two purposes. Also since its close quarters it keeps you warm if needed or nice and cool without the fly. Check em out see what you think.