I don't like my friend's other friends

About what?
You either get to know them or you don’t.
Not much to be done about it. He has friends that are in his life. If you want to stay unit then you need to find a way to do so.

I don't know how I will speak to him without speaking to them

People like that are the worst, I relate.
I would recommend staying polite and courteous when you're visiting your friend and they happen to be there, say hello, make small talk and then don't go any further. You don't have to pursue a friendship with them unless you want to, friendships are two-way. If your friend asks you to hang out with them, just say you don't want to, and make plans with your friend one-on-one.

Then you’ll lose him.

I don't want to talk to them at all, they are too damn academic and they are too rude they need to have some respect

Well then don't. Walk straight past them into your friend's room and ignore them saying hello to you. Might be a bit awkward, and I don't think your friend will be particularly pleased, but if it really pains you that much then go ahead, there's no one stopping you.
I personally think that in life there's always going to be boring, annoying people you have to interact with, and it would probably work out easier to say a quick 'hello, nice to see you again' and walk into your friend's room, but you do you!

I don't want to talk to them at all, they are too damn academic and they are too rude they need to have some respect

Why do they need to have respect?
Respect is earned not a given.
You keep calling them “too academic” just because your friend and his friend are going to university doesn’t mean they’re bad or snobs. It’s a perfectly normal thing to do.
You’re on a different path, which is fine. But you don’t just get to discount theirs.

Their questions about your exams etc. just indicate that they are as awkward as you are so struggling to find anything to talk to you about at this stage of your relationship with them. As you get older the questions from people you don't really know will become about the weather, gardens, cars etc. Anything to make a conversation.
This is not something you should worry about. Either you'll find some topics of conversation with one or two of them or you'll simply begin to ignore each other.
The big question is how are you getting on with your friend?

My friend messaged me if I want to come out with him and a few of his mates from 6th form so I thought sure so I went over to the 6th form at the finish time to finish them. They seemed alright at first but they are very academic, they kept asking me what exams I'm doing and what university I'm going when I never said I was going. They are just too academic and I don't like academic people. My friend is academic but I have been friends with him for years so I want to stay like that and I didn't know he was until recently. My friend just said after I should come out with his friends again and I don't want to but I find it hard to say no. I don't really like his friends, all they talked about was, a levels, university and results. It's a grammar school 6th form they go to as well.

My friend is going university with these people in accommodation and he said I can come to visit but I don't know what I'll do because his friends will be there and it might be the only way of seeing them. They just seem a bit stuck up and stuff. I want to see my friend but I'm going to have to see his friends because they'll be in accommodation. I don't know what to do. My friend might not be able to meet outside because he'll be studying a lot.

What do I do?