Supplying photos or .ai files is hit and miss.
Every fabric is different and the patterns need to address the fabric used, including stretch, shrinkage, the way it is cut, if it can be embroidered on, or printed, as well as any required collars & cuffs, which are of a different fabric and would have to be colour matched when dying.
For a factory to supply a finished sample that ticks all the boxes and is the "perfect" sample will take, on average, 3 samples.
Include the courier costs, back and forth from China to UK and the sampling costs will be expensive.
Better to supply a garment which fits correctly, uses the fabric you want and use this as the template.
Amendments, embellishments, embroidery, printing, grading & personalised packaging and labeling can be added.
Its a tried and tested formula, especially when manufacturing in China.
This is with 30 years experience in this field.