How much can I expect to improve in 1 year?
Without knowing any more detail, the goal is probably achievable but you won't do it by riding harder, you need to train smart(er). 

Given you just started cycling, if you have not had any coaching, you are probably close to fit enough to do it with improved techniques. You should therefore focus on training, not riding.  If you train to ride, rather than ride to train, you will become a stronger rider.  How much training vs riding is up to you - no point spending all you time training, especially if you don't enjoy it as much.  

I suggest getting involved with a local cycle group, and maybe seek advice from a cycling coach. If you don't want to use a coach, look around the internet for training ideas and plans.  Be careful not to overdo it.