Short answer is yes, if it was my garden I would use it. However there are some issues, and perhaps a better alternative if you are unsure. Stay tuned.
I would treat it as a regular fertilizer, carefully on some crops which might not respond well to a sudden influx of N such as tomato. We really need knowledge of the current existing state of the soil, is it acid or alkaline and is it deficient in one or more of the essential nutrients. The best source of information on that issue is to review the performance of the crops grown on the allotment in the past few years. Were the crops satisfactory, and were there any that showed particular problems such as NPK or iron deficiency.
The alternative solution that might be safer if you are concerned, is to offer the fertilizer to a tennis, cricket or golf club where they need a specific grass fertilizer, and then ask them for the clippings in exchange. You get the benefit of fertilizer that has been cycled through growing plants. Use the clippings either on compost pile or as top dressing in rows of potatoes or other plants where there is a benefit to reducing moisture loss at the soil surface during the growing season. Worms will pull the clippings underground at the end of the season when you remove the crop.