I have never heard of an English show that REQUIRED spurs (except for upper level Dressage). I would seriously question whoever told you that, and check with the ACTUAL show secretary and/or rule book.
It would help to know what country you were in, since you don't have anything in your location box. It would also help to know if this is a recognized show or a "fun" show.
If spurs are absolutelt necessary, then ride with very short humane spurs and ride with them very low on your boot. Keep your heel down and toe forward to minimize their impact.
"To be an equestrian in the classical sense is not just to be a rider. It is a position in life." --Charles de Kunffy
Anti-Slaughter and Proud!