My main piece of advice is to develop a thick skin and perfect your arched "got a fucking problem, mate?" eyebrow because there will be times when you need them. Your parenting will be held to a far higher standard and level of scrutiny than that of parents who have NT (neurotypical) children. You're expected to be saint-like - "I don't know how you do it! You're an angel!" - as well as omnipotent- "you should have known in advance that your child would act in this totally unpredictable way in which they have never acted before now!"
Basically, sometimes it's going to be rough and sometimes people are really going to piss you off. Thick skin, raised eyebrow. You are doing your best regardless of what Brenda in the supermarket thinks.
People will send you a bullshit poem about a holiday to Holland and they will say inane things like "God only sends special children to special parents" and "are you sure he's autistic? I wouldn't have known if you hadn't told me". They will ask what his super power is, I tell people my DS can fly but that we've told him not to do it in front of the normies. They will offer parenting advice ranging from benign (ban screens) to the batshit (good hard smack). Most of them mean well, I guess. Try not to take any of it to heart.
Get a good support group. The SN (special needs) boards here are always good for support and advice. Google the name of your area and 'autism support group', it'll bring up some local to you. If you're in NE England, I can recommend some for you. The National Autistic Society website has a lot of information that can helpful including reading recommendations.
It's not all doom and gloom. I wouldn't change either of my sons (both autistic) because I love them and autism is an intrinsic part of what makes them who they are but if I could remove the negative aspects of it and change the world to better support them, then I would. It's okay to be scared and worried about what the diagnosis means, it's okay to be a little bit sad about not having the child you thought you were going to have, it's okay to say that if autism was a person you would kick it square in the face but don't let these feelings distract you from your little boy. You'll find your way. My boys are funny, sweet, they give the best hugs. We have some truly awful days and sometimes I think the hugs are maybe their way of making sure I don't chuck them in the nearest bin but they're mine and I can't think of them as being any different to how they are.
And I know this last one is difficult but as a carer, make time for you. Even if it's just ten minutes with a cup of tea and something mindless on the TV, you need that time for yourself to let your mind switch off.