I moved into a property 2months ago and the house had a bit of damp in it so the landlord give me two tins of damp proof paint and said that will get rid of it so I spent a fortune on doing up my house and the damp is back and worse it is making my wallpaper peal off the walls and my daughters cot is covered in mold so now she has no bed, the landlord has offered to move me soi went and viewed a property which had mold all over the walls and is in worse condition than my house what will happen if I withhold the rent until something gets done about it or he moves to another house with no damp? I found out my house has had a few tennants come and go cause of the damp and he knew the damp proof paint paint wouldn't work but yet he still let me move in with a 4 month old baby at the time and now it is affecting her health.

Have you reported the conditions to the health or housing department? You need to follow the rules for your area. Once you have properly reported it, and the landlord doesn't fix the problem, then you can either withhold rent, placing the rent in an escrow account.

So what will happen if I just move out and take the rent with me for the damage to my wallpaper, carpets and daughters cot?

The landlord sues you for unpaid rental and damages. Again, you have to do this right!

OK but I can keep hold of the rent until the landlord does the installation in the walls and the damp course and until he refunds me for the damages like the wallpaper and my daughters cot?

Did you read what I said? You can't just decide to withhold rent. As soon as you do, the landlord will give you a pay or quit notice giving you 3-10 days to pay up or vacate. But, if you do it right according to the rules in your area, if he tries that, you walk into court, show the judge that you have properly reported the problems and they they have not been fixed. The court will, then (most likely) rule in your favor. But if you can't show that you have followed the proper procedures, the judge will rule in the landlord's favor.