Most places in England it has not been wet enough to sow grass seed without assisted watering the last couple of months. Raining lightly on and off for a week isn't enough. You need it to rain regularly and copiously for more like three months to establish a lawn from seed, or else water it. It typically takes the seed about 3 weeks to germinate, and during the period after germination any dry spell will kill the little seedlings, they are very sensitive to dry during this period as they have very little root system. This is why the best time to sow grass seed is early autumn when nature is more likely to supply the required, than spring/summer when dry spells are the norm. Though if you do sow in spring/summer and water it religiously, your grass will germinate and grow faster.