Sounds as if long runs are going well.....even if sometimes it doesn't feel like it! Don't forget you're running on tired legs now, you'll have tapered approaching the marathon and it will be easier At least that's what I'm telling myself! I did 20 today, in 3:10 .. Not planning to do anything longer.... But generally am doing my training runs on hills and/or off road, so I reckon it's long enough.
Lars, I'm a first timer, so no expert, but my understanding is you can enter and then qualify, that's certainly my plan! My marathon times, ambitions seem similar to yours, so far never done more than a marathon, but am looking forward to the challenge!