Charlie, you need to post a link if you are asking about a lady. If you post a link, someone on here can probably comment.
If you are going to take them for a drink/meal you will almost certainly have to pay for their time - as well as the drink/meal. You should be able to negotiate a reduced rate for 'social' time. You probably also need to make sure that they are presentable enough to take out.and can carry a conversation before you take them out (if they are EE) or your social time won't be very social. May be best to leave the social time until you have seen them in the flesh at least once, or not bother at all. You could take a bottle of wine with you to the booking to drink together as an ice breaker. Beware of treating it too much like a date, or lines could become blurred in your own mind. Probably best to concentrate on the main prize!!!
As far as going rate is concerned, how long is a piece of string.........!!!! You should be able to get a decent girl for £120 odd, but there are some good girls who are cheaper. Others on here may disagree on that price.