Yes. To be short, I think it is possible.
I don't know much about distance learning or taking GCSEs at college, but for me the main factor in getting those 8s and 9s is your personal dedication. If you decide to set yourself that goal, and STICK to it, you should be able to. I think it might be quite difficult- I got all 8s and 9s based on a solid two years of year 10 and 11 but if you choose to study smart (eg look at the specifications for each of your subjects, they were my holy grail last year) catch up is always possible. Plus, if you're taking them next summer, you're probably more likely to do well because current year 10s are missing out on a lot of their teacher contact, meaning the grade boundaries might be a little bit nicer.
I think the best thing to do is try and talk to someone at school or college to see what they think is the best route. Being a year behind at sixth form isn't a big deal, there are a few people who have taken gap years due to mental health or other reasons at my school at least.
If it seems like taking GCSEs after one year is the best option, just get your head down and work your ass off, basically. 8s and 9s are the most difficult grades to get, therefore you have to be working harder than everyone else. But they are attainable, so no need to be too worried.
Hope that helps a bit lol