The address for the church is 10503 Slide Rd, Lubbock, TX 79424. It's about 4 miles from the hotel you're staying in.
If you will be riding to/from the hotel, negotiating a safe passage on/around the Loop is tricky when weekend shopping traffic picks up around 10am, but you shouldn't have it too hard. Going out, just travel west, hit Quaker, then turn south. Go all the way to 114th street before making a break west for slide road, and return the same way coming back into town, taking Indiana back in instead of Quaker.
I'd contact the ride leader ahead of time to make sure they are on for that Saturday just so you don't find yourself out there alone if they don't get together that day. If you do end up solo, FM 1585 (and even 114) makes for a fast long/flat ride, and if you hit it going east you can ride to Slaton and back without turning off that street. That'll give you about 50 miles round trip. More if you go past Slaton and through Ransom Canyon where some of the Tri bike portion is being held.