When a lawn is going to be subject to heavy use,such as a play area,a good hard-wearing grass seed mix is essential.Look for a mix including Cynosurus cristatus,Crested Dogtail.
this will be less close growing than many finer mixes,requiring less mowing.
The optimum times for seed sowing in the UK are March and April in the South,April and May in the Midlands and North.Be aware that grass does not grow well in shady conditions,requiring
constant attention.