Thomas Street Studios Ltd review: Modelling contract

I have attended a photo shooting with my 15yrs old son yesterday. During the initial phone call invitation few days before and in there email all they explained was that the portfolio will cost £299 and that polo models will liason with agencies if my son's shoot is successful they said nothing about packages and that the liason service only comes with packages starting from £1500 and we must decide on the spot.
After the 3. 5 hours shoot we were told my son was successful and were sent to see Mr X in his office, who was very welcoming and nice, but very misleading in the way he presented the information, he became very pushy and impatient when I was reading the contract. He made me feel I am waisting his time and ashamed for asking questions. Being tired after a 3 hour commuting to their London studio in white lion street and 3 hours waiting for the shoot to finish I was exhuasted! the truth is I felt very pressured when I was told that I had to decide on the spot else all photos will be discarded. Pressure pressure pressure all I felt! From one side we were given no time to think it over and decide especially that I could not discuss it with my husband and on the other side, my enthusiastic 15yrs old who I didn't want to break his heart! On top of that the whole situation had put extreme pressure on my mental state as I suffer from anexiety.

Despite the fact that I have signed a contract that cannot be cancelled, I am hoping we can cancel the contract, especially that my husband objected completely of my decision and believes I was mislead.
Finally I feel extreamely ill of being in this position and thankfully have contacted the citizens advice bureau who advised me of what to do.