what to do when you are incredibly bored?

I am the exact same as you. I'm always bored and I ask questions regularly on here asking for advice on how to cope with the boredom. My advice is maybe consider going back to education It would be a good way of getting you out of the house and helping you stay connected to the world

If you have PTSD especially, you definitely need help with that.
If it's military-related, most countries (including UK I'd assume) have programs for PTSD that you could take advantage of, and some might be phone-only in the beginning if that's what you're most comfortable with.
https://www.google.com/search?q=UK+PTSD+help
https://www.google.com/search?q=UK+depression+anxiety+help

Having a dog has helped many with PTSD, particularly those that have been trained as PTSD service dogs (sometimes free) to help with those specific symptoms (and will always provide companionship, fun, unconditional acceptance/love/affection, etc, too).
https://www.google.com/search?q=UK++PTSD+dogs

(Also check out the info/etc in my answer to your similar question yesterday about having few supplies/equipment/money, etc.)

I do crafts, though your a man so maby try writing a book. Its the perfect way to get out you imagination. I'm in the prosess of writing a story. It is just a little tale thats been in the back of my head forever and I finaly got some thing to write in.

Depends. If I haven't exercised or done physical work lately, I usually prefer something physically active.

Otherwise, I enjoy biking, surfing the net, movies, and YouTubing. Lots of other things too! Just enjoy!

If I were in Manchester, I'd go after fifteen things, seeing and learning about the city's incredibly rich history, with or without other people. I've had my war, and know enough of what triggers my flashbacks to either avoid them or tuff it out. Meantime, there's this electric cyberworld. I've visited several countries today, and learned things, which never ends.

Have you ever visited with somebody who is into Amateur radio? It's also called Ham radio - it can be a lot of fun, and with your own radio station, you don't have to leave the flat.

i have condition similar to you,in addition that i live in Iran.i try some spiritual solutions.till i read this from wayn dyre.
1) all your limitation is concern to your body
2)you are not a physical body with the spiritual experiences,but you are the sprite with physical experiences

Read a book. Then read another. If you have a library card, you can often download ebooks from your library without leaving home. Check the website of your local public library.

You must face your fears. If you are afraid to go outside you must be brave and go outside. It could even be exciting to grab the bull by the horns, as they say in the US (not sure about the UK). The Bible has a proverb that says some people claim they can't go outside because there is a lion out there and they will be slain in the streets. They want you to avoid that way of thinking. Life is full of dangers and threats but we can't avoid these risks. .

Masturbate.

Jk, try some kava kava. In some cases, it's just as effective as benzodiazepines, but without the adverse side effects. I have GAD and consume the stuff myself.