I've not been to any in Bradford, but I have met a few girls for hotel incalls in Leeds. I get what you are saying, the first time I was shitting myself wandering what I'd say if I got caught, but I've probably done it 5 or 6 times now in 3 different hotels...as long as you look confident when walking in, there isn't a problem. Make sure you know which floor and room you are going to, and just head for the lifts (a good WG will give you a description of where to find them) and tap the numbers in. I tend to play with my phone, look busy so nobody asks questions.
A lot could depend on the time of day, some hotels might have security or more staff on at night, so that's something to be aware of. My hotel punts have all been during "office hours" so I've not had that come up as a problem.
Again, a good WG will have scoped out the hotel...again, it hasn't happened to me but I imagine it's bloody awkward if she has to come and let you in or through security doors with a swipe card or something!
I've also come to the conclusion that all city centre hotels have at least 1 resident prostitute at all times