Hi OP. My DS is 4 and has a very severe language delay and is starting reception next week.
I know how you feel. Believe me I do. I worry about DS future, worrying about how his going to learn the things at school, if he already has difficulty learning and to use language.
But it came to the point that I was too fixated on what is the issue in his delayed talking. When I really should of been using my energy to help him.
DS was toilet trained at the age of two, I thought his speech would delay him. But it didn't at all and it took him 2-3 weeks.
I wouldn't bother with the potty if I was you, but it is your choice. When he was learning, I didn't use pull-ups or pampers on him. I either used just the cotton pants or leave him naked below the waist area.
I would then sit DS on the potty for 10-15 mins for every 30 mins.
If he did a wee, then I would praise him. If he happened to wet himself, I wouldn't get angry or anything, but I'll let DS help me with clearing up his accidents, teaching him to pull his pants wet pants down and putting this into the laundry basket. I also taught him to pull his pants down or up when going to the toilet. Ask the nursery to assist you in this when he starts.
When it comes to toilet training, be committed, not saying your not. But I took it as if I was toilet training DS one day but not doing it the next day. I might as well start toilet training all over again.
Regarding the communication issue at nursery. If your worried about people not understanding him, he can use PECS or if not assist that they use some basic Makaton signs for the staff to use, alongside using communication aids, pictures etc.
The site: www.teachmetotalk.com has a looooooooot of resources about speech and communication needs. I brought a few of her stuff and because DS statement will not be ready on tips. I've got some tips and info that the school can be doing.
Also google ICAN, they are a communication website and you can book to talk to the speech therapist. They even talked to DS nursery about how to implement language in his time at nursery and how to support his needs.
Also. I world start off with the statementing process now! I wish I done this sooner.