Getting my 4 year old cat Neutered :(

Hi, I have a 4 year old cat that has been spraying everywhere and everyday for the past 2 years, I have booked him in to be Neutered.
I have read lots on when you should get your cat Neutered which should be done in the early stages and it has been worrying me because he is 4, should I be worried about getting him done at this age? The funny thing is, when he was born I didn't realise he was a boy, for years I thought he was a she but obviously not as the smell was terrible. 
Another thing is that he is out everynight and he only comes in for food or to sleep abit, but when he comes home he is full of scratches, his fur is matted, and his eyes look sore. Hopefully having him Neutered will make a massive difference because I don't want him to be in that state. 
If anyone could help it would be great, Thanks! 

Unaltered cats tend to get into fights, especially with other unaltered cats because they can smell each other. Competing males will fight for territory or females, so having him neutered and keeping him indoors (especially if he's gotten in fights already, and he'll need to stay inside to heal after the neuter) is the best thing you can do. For all you know, there could be a resident tom who's just always picking on him, or he keeps wandering onto their "turf". If he's going to the vet for surgery, it doesn't hurt to have him physically assessed to ensure his injuries aren't bothering him.

Some cats may continue to spray out of habit even after they've been neutered, but it depends largely on the cat. There are no guarantees. If he's sprayed inside your home, you can try to clean the scent with an enzymatic cleaner so he may be less likely to re-offend on those spots.

Thanks for that. I will make sure I get the vet to check over him. I just don't want them to think that he is in bad condition because hes out all the time! but overall he is a well looked after cat and spoilt rotten! Its just the smell, the scratches and matted fur that makes him look like a stray cat!

Perhaps after the neuter, you can make a daily routine of brushing him as well. He'll probably get into fewer fights anyway, but having nicely brushed fur can also feel GREAT for a cat (some mattes can be so tight or bundled up that they hurt and pinch the skin). A vet should never judge you for wanting to do better for your cat, and if they ever make you feel like you're being looked down on, I would say you could find a better office with friendlier staff! Never be afraid to ask questions of the vet or techs and be honest with them too. You're both invested into good care for your cat, and that will be your shared goal.

If you fear he may actually be picked up as a stray by a stranger, something you can do (if you haven't already) is look into microchipping. If he ever gets picked up by someone who thinks he may not have a home, a humane society or vet can scan him and find your contact information to call you and verify he has a home.

it is very important to neuter your cat. When I was at college I had a cat, he was an outdoor cat and always come back full of scratches from fights, he died a painful dead when he was 5 due to an infection he got from other cats while fighting outside. It was really sad and we regret that we didn't have him neuter on time.

2 years ago I got a kitten, he was neutered when he was like 8 months. His behavior changed for good, he still likes to go outside but he doesn't fight anymore, so please don't hesitate on doing it. ^^