Hi quite hard in the Midlands. Check out quarries on Google Earth that washes aggregate. Might be better to head to Bristol/Weston estuary where options are endless. Always check tide times and be careful.
Not sure which part of the Midlands you are in but I have put a few locations on the mud map https://www.quicksandfans.com/bb/viewtopic.php?f=10&t=17493 and they are between Nottingham and Grantham. If you want any more info or pics let me know