In the early stages your child may be seen by salt for feeding or swallow issues and then later on for speech. You can be referred though HV, Paediatrician or school

Physio will look at your child's gross motor skills and will be able to provide sessions and refer for aids such as wheelchairs or additional needs pushchairs & Standing frames. You can also ask them for a referral for a therapy trike if your child can not ride a standard kids bike. (trikes are not funded by NHS)

Its advisable to have yearly thyroid blood tests. Also using this appointment to go over any other concerns so they can be looked into and be referred  to the relevant people.

Down syndrome association has a great check list on their medial series for Thyroid . link below

There are many things OT can help with...

Mobility, toileting, eating, seating or school aids.  

They can offer support to school on best learning aids for children with ds.

People with Down Syndrome have very small airways and struggle with a common cold. They are also prone to tonsilitis , sleep apnoea and respiratory issues. Also aspiration of liquids is common.

Your child may be seen by a dietician if they are struggling to gain weight as an infant. 

Or to be monitored if they have thyroid issues.