Posted: 17/06/2017 at 12:28
I recently had a similar problem (without the dandelions). Lawn was uneven and during last summer patches of brown appeared. During April the entire lawn was rotovated to remove the old grass which was then composted, ground was re-levelled and good quality turf put down. Bought a new sprinkler and kept it watered every day (1 hour per session 'we have a water meter!!!') and didn't walk on it until it needed cutting ('twas 3 weeks). Lawn now looks excellent.
We have used a company to come 4 times a year to spread fertiliser on the lawn (no names mentioned) but to be honest I have found them to be a complete waste of time and money so have given them the flick (as they say).