Help, 4D ultrasound concerns !!

Some people have been telling me that if the baby is in your pelvis it will be hard to get a picture also i'm 35 weeks and have my appointment next week well I want to know if its really worth it ? Like what if we go in and they cant get a picture do we still have to pay ? Some girl I know got one at 34 weeks and it came out nice i'm just hoping mine does too because I havent had much ultrasounds besides the first two and the 20 week anatomy scan one. This 4D pic is all i've wanted my husband never agreed because he thinks theyre creepy and give your baby too much radiation but I don't agree . 
He finally said yes so i'm really excited but nervous at the same time. Also what can I do to get the baby to move during the ultrasound? Is it the same as the 20 week one ? , drink something cold or orange juice , candy , something sweet etc