Cut high, cut often, never take more than a third of the blade at once, and fix the cause of moss rather than the moss.
A British lawn is mostly a question of mowing height, drainage and whether the grass is being asked to grow where grass does not want to grow. Most moss problems and most bare patches are symptoms of one of those three rather than problems in themselves.
What it covers
Every tip in lawn
Higher than most people do. Around 4cm for an ordinary family lawn, and never remove more than a third of the blade height in one cut.
Moss is a symptom of shade, compaction, poor drainage, low fertility or cutting too short. Killing it without changing one of those means it returns within a season.
A high-nitrogen feed in spring, and a different autumn feed high in potassium and phosphate. Using the spring one in autumn produces soft growth that disease attacks.
Scratch the surface up, sow seed mixed with compost, firm it down and keep it damp. Spring and early autumn work; midsummer usually does not.
Generally no. An established lawn goes brown and dormant in drought and recovers when the rain returns. If you do water, water deeply and rarely rather than lightly and often.
Tipking is general household information, not professional advice. Test anything on a hidden patch first. Full disclaimer.