If its that thick with dandelions, dig the area and remove all roots of the dandelions, and I mean all, don't leave any behind, rake over and level, tamp down and put some seed down. Or turf, if its a large area.

I've got the same problem lots of dandelions, i do'nt want to reseed yet, digging them up is the best way, i keep on top of them with a table spoon of salt put in the crown of the dandelion ( on a dry day)

thanks i have started the digging its now 16.25 i started at 11.30 and am not even finished i am extremly warn out now. start again when i get a bit more free time. ive at least had one idea which im going to increase the depth of my flower beds once ive finished this.

Good idea HChristy - as far as I'm concerned, borders and beds need to be pretty deep to get effective planting.