Garden Fence

My back garden is currently fenced with a wooden post-and-rail fence. The total length of the fence is about 300 yards. Most of the posts are rotting and would need to be replaced. The rails are still mostly ok. Please quote the total cost of supplying new fence posts and of replacing the fence. I would need your guidance on which type of posts to get – preferably ones with some sort of treatment to prevent further rotting.

I would also like a 3 foot wooden gate to be fitted into the fence. I already have the gate and the gate posts but you would have to bring any tools and cement needed for securely fixing the gate posts in place.