If you haven’t got a relevant degree, you can consider live online courses which will allow you to train as a quantity surveyor without any previous on-site experience. The College of Contract Management offers an Advanced Diploma in Quantity Surveying which only requires a Level 3 qualification in Engineering, Science or Maths or GSCE grade C or above in Maths and English.
https://www.theccm.co.uk/courses-page/quantity-surveyor-course/