I want my hair to grow longer what vitamins etc could help to speed this process?

If nutritionally...: If a person is nutritionally in good shape, without any major disease nor illness, then her hair will grow at the same rate with or without vitamin supplements. The usual multivitamin supplements that many people buy over-the-counter do not change the growth rate of hair.

Biotin: I agree with dr. Kwok that barring major illnesses or nutritional deficiencies, your hair should be healthy and growing from your food intake without supplementation. However, biotin may be a reasonable help. Also making sure your diet contains sufficient omega-3's is important for the texture of the hair you do grow.