Not correct. The jeep they used was filled with propane canisters, petrol and nails. The Ammonium Nitrate acts as an oxidiser, and these guys didn't have it.
Propane canisters are designed to not explode. The Glasgow terrorists clearly thought that if they just lit a fire under one of them it would explode (playing too much GTA methinks). They didn't even attempt to make proper explosive with an oxidiser.