The pilot reported that the purpose of the flight was for his biennial flight review (BFR). During the approach to landing he utilized 20 degrees of flaps and side-slipped the airplane. However, while beginning the landing flare the airplane encountered a gust of wind and impacted the runway with all three landing gear. The pilot was able to taxi the airplane to the hangar, where he inspected the landing gear and noticed damage to the nose gear tire. According to the certificated flight instructor (CFI) the airplane landed "relatively flat." Subsequent inspections revealed substantial damage to the lower left portion of the firewall. The wind about the time of the accident was from 300 degrees at 10 knots with gusts to 19 knots, and was variable in direction from 270 degrees to 340 degrees. Both pilots reported that there was no preimpact mechanical malfunction.