Tegan - it's never too late to teach a dog new tricks. My current youngest dog is almost 4 and has always snuggled up on the sofa with me in the evening. About a month ago I decided enough already - he was jumping on/off, wrecking my knitting and generally being a pain. I bought a new big dog bed which lives close to the sofa. I told both dogs "off, on your bed" - the first few nights they couldn't believe I meant it. It was not relaxing but I persisted. Within a few days, the older dog simply stopped trying to get on the sofa, within a week, younger dog would go and lie on his new bed. He occasionally tries it on but I just tell him ' off on your bed, and off he goes.
I wish I'd done it years ago frankly, much more relaxing, easier when friends who don't necessarily want a dog on their knee.
My friend's new leather sofa has been wrecked by her daughter's dog who is living at grannie's. She did use blankets to protect the leather seats but sadly, they didn't work.
Best of luck with this one!