Posted: 25/04/2017 at 11:08
I think your lawn is too young to scarify just yet.
Don't use the Westland Aftercut all in one weed and feed if you have or are going to use the lawn seed as most of this type of product contain stuff that inhibits seed germination.
I would get a Daisy Grubber http://www.whittingtons.biz/garden-tools/hand-tools/spear-and-jackson-elements-daisy-grubber/p39518.html?gclid=CPOw-6utv9MCFe0Q0wodwMsD8w and use this to lever the dandelions out of the lawn, trying very hard not to break the long tap root which may well regrow if left behind.
If you have problems getting down on your knees to do this, you could use Roundup Gel weedkiller and dab some on each dandelion plant - within a few days the dandelions will be shrivelling and dying.
Then you can give the bare patches a gentle scratching over with a rake and scatter your lawn seed and water it in.
Hope that helps