Should I use a complex fertiliser like NPK 12:32:16 or buy DAP and urea separately?

Both approaches can work; the right choice depends on what your soil and crop actually need. A complex fertiliser gives nitrogen, phosphorus and potassium together in fixed ratios in one granule, which is convenient and ensures the nutrients are placed together at sowing. Straight fertilisers (urea for nitrogen, DAP for phosphorus, MOP for potash) let you adjust each nutrient independently to match your soil test, which is the more precise and often more economical route if, say, your soil already has enough phosphorus or potassium. The key is to match the product to your soil's needs rather than picking whatever the shop pushes. If your soil needs a balanced N, P and K start, a suitable complex at sowing plus urea top dressing later is a clean plan. If your soil test shows one nutrient is already high, straights let you skip or cut that one and save money. Compare the actual cost per unit of nutrient, not per bag. Decide based on your Soil Health Card or soil test and your KVK recommendation for the crop, and do not over-apply any nutrient.