I`mstuck at the point after you get lethos dream and you get mobbed by a bunch of harpies any help would be much appreciated

Those harpies are a tough fight. Individually, harpies aren't much of a challenge, but this is a bloody great mob of them. Suggestions:

Don't get surrounded. There's a narrow space (to your left, if you're facing away from the projector); get through it and stand your ground behind it. Use Yrden to jam them up.

Use anything you have that can do damage to a crowd. Bombs; area-effect Igni.

You could prepare the Yrdens before you touch the dreams, as well. :D

Quen'ing immediately before touching dreams is also reasonable.

Use strong attacks.

Harpies tend to be pretty slow, so using strong attacks (which have more of an area effect and can stagger surrounding enemies) can be invaluable. The red haze bomb, if you can make it, is also a good idea because it'll basically turn some of the harpies against each other and let you pick them off while they're distracted fighting each other.

Dancing Star is my favourite type of bomb, and it works wonders on groups of harpies. Otherwise, make sure you stay on the move, so you don't get cornered.

I believe that in latest patches, harpies have been said to be immune to traps (and thus I think to Yrden too). Quen had also been nerfed, but it's still a must in difficult fights.

Any way, against this mob of harpies, I also recommend bomb spawning and rolling around till the weaker harpies are down. Then you can take of the strongest opponent with strong attack.

Immune to traps? Really?
I wanted to do my 1.3 run on insane (finally), and that would be a very nasty surprise, as my plan for that encounter relied on traps...

I found I had to really try to take them on one by one as much as possible. There are a lot of narrow passages between the more open cave areas, so use those to try to thin out your attackers.

It would make sense for the harpies to be immune to traps; more accurately would be to say they fly over traps and thus never trigger them.

Except for harpy traps woohoo.

whoopee I finally got through thanks for all your help I found running around a lot and topping up the quen as the best way for me to do it

Tried this with patch 1.3. The birdbrains definitely get stuck on Yrden, and if you catch the one at the front of the mob in a narrow place, the others all get jammed up behind her. Then Dancing Star bombs make short work of them.