It will be difficult to find unidirectional because that is so fragile and prone to splitting. Unless you mean uncured material, which is called prepreg. Lots of manufacturers. It is not easy to get small quantities, though.
We have done many UD sheets in various thickness (0.2-3mm) for a costumer in the past. Tricky, but can be done as soon as you used a lot and effective release agent and be very careful when de moulding.