My ds isn't in mainstream anymore but a quiet area would have been good. Not necessarily just for my ds but somewhere he could go as a time-out if things were getting too much - to read/draw or something calming. And enough room to walk between tables.
Echo what Seuss says. Some sensory equipment/toys (not necessarily in the classroom but nearby. A box of reinforcing items particular to the child, to motivate and reward (esp relevant for those with ASD).
My ds doesn't have significant SNs, but his school has a unit for children with behavioural problems, and he used their quiet room when he couldn't cope with the school environment. It was really helpful both as a reward and as a calming down place (he used to throw extreme tantrums).
My 2 are in mainstream and most important is a space to take them when they need quiet! And a place to do 1:1 outside of the classroom - for salt etc, or to work on the classwork with their LSA when they need extra help to understand the work and need it explaining in a different way. A beanbag area to throw themselves onto as well
I think what's important is to have a policy as a school to respond to individual needs and have assessments so that individual needs are identified because you can't possibly sort out everything that might possibly be useful for any child with any one of a million types of sn, that might at some point be in that classroom, iyswim.
The other major problem with using the corridoor is that for children with poor listening and attention skills there is loads going on. My daughter's MS school was built knowing there would also be kids with SLD and is not fit for purpose.
Rather than setting aside "special" activities for the child with sn it is often easier to include all of the class or at least a small group with the activity aimed at a the child with the sn.
For example the visual timetables are used & there foe all the children in my ds2's class, the hall also has visual timetables braking down lunchtime. DS2 just has a prompt fro his 1 to 1 to look at them.
The OT sensory bag whilst helping ds2 with his sensory sensitivities was used to teach the others about texture & materials.
The exercises that the physio sent to the school are built in to the PE lesson.
All the teachers use makaton throughout the school.
Its not so much that i think that schools need items & things (well not for my ds at least) but many schools need to alter their attitude to really make inclusion work.
Oh & the quiet area would help too! My ds's work with outside agencies is often done in the staffroom because there is no spare space. SO a flexible space that outside of the classroom would be good.
ds is in ms nursery, which is part of the school, the good things are that they have a base, with a ball pool/soft play room, plus two other rooms which are for time out of class type activities (one is geared towards SN, the other is for all children).
atm my ds gets lots of attention and help from adults in the school, working in small group activities with other children in his nursery class, helping him with social interaction.
he has visual timetable and a sand timer(egg timer thingy) to help with transitions.
My DD2 started mainstream school this term. I agree with Anon in that integrating the child by incorporating their needs into the rest of the school is great.
I am really pleased so far with DDs school's attitude - the children are learning Makaton, parents have been asked for permission to allow their child's picture to be put on her Dynavox so she can 'choose' to play or work with them, and they have a dedicated bathroom for children in nappies that has a shower, accessible toilet, a changing bed and large taps etc. Simple things that really help - I know she's not having her nappy changed on the floor in a corner of the classroom...
They've also got some beanbags in the book corner so she can have a snooze when she needs one.
space. for moving around. for storing bulky equipment (wheelchairs, walking frames etc) clearly recognisable 'areas' of open plan space. level access to toilets/ playground/ assembly hall. inclusion for 'group' activities, not physio always at the same time so they miss out on singing assembly etc. understanding that if you put supportive seating on the outer edge of the classroom and all the musical instruments in the middle, the sn kids are going to be last in the mix every time the teacher says everyone get an instrument. thought and planning as to inclusion and accessibility techniques for all activities.