Does anyone know if you can book via text message or do you have to call?
Just give them a call. If you book a day or more in advance, give them a call on the day to make sure the girl has turned up. In the shop it's a £10 door fee, plus £70 for half an hours GFE. In the apartment, it's £80 without a door fee. So it makes no odds.
If it's your first visit, it's like anywhere else; just give yourself an extra ten or fifteen minutes to find the place and the best places to park. You can always park within a couple of minutes walk to either venue.