Marks and Spencer do a great uniform range that has less /smooth seams for those with sensory sensitivity and also accessible features such as velcro instead of buttons.
http://www.marksandspencer.com/s/kids/school-uniform/easy-dressing-school-uniform
SERC / Newbridge School
Barley Lane Campus, 258 Barley Lane
Goodmayes
Ilford, IG3 8XS
SERC is a service and information centre brought to you by Redbridge.