Have alook at www.superspray.co.uk they sell a liquid feed in 5 litres called Lawn Magic. You apply it with their superspray hose end sprayer. It costs about £20 for 5litres delivered to your door. professional stuff! it works really well and goes a long long way. the plant feeder costs about £10 but you can use it for other things like washing the car or greenhouse.

I prefer to use liquid feed as there is no risk of the grass browning if it doesnt rain soon after as with pellets. Its easier to get a more even feed so you get a more even 'greening' on the lawn and the feed goes 'straight in' so to speak. Using this hose end feeder attached to the hose pipe means its much quicker and less of a chore. the sprayer holds 600ml of feed which when sprayed will cover 60sq.m of lawn.