Do you mean the front page 'adult content/over 18s' disclaimer that Medea is describing or the 'time and companionship' one that appears on many escort websites? I believe that the first one is a legal requirement, but I don't know the details either - you could try Google for detailed legal information.
The other disclaimer originated in the US where prostitution is illegal - it is a mainstay of agency and parlour sites in the UK in order to try and keep the proprietors on the right side of the 'controlling for gain' section of the prostitution laws, but if you are independent and in the UK you don't need to include it, even though many ladies do. As it is not a requirement, you can word it any way you like.