Posted: Today at 14:33
Apply a weed, feed and moss killer - all one product- to the lawn in April when it is a bit warmer and the grass is growing well. When the moss turns black, depending on your fitness or size of lawn, either rake it out using a spring tined rake or hire a scarifier. any bare patches of lawn can be reseeded.
Cut it regularly once a week keeping the blades quite high i.e. Don't scalp it and the come the autumn you can put down an autumn feed.
is it a new build or just new to you?