You are over the first stage where the cycling is starting to take effect but-------------------------------------- there is always a but. Cycling efficiency and fitness comes in stages and you have only reached the end of the first one. For a while you will not notice a great improvement and you can think you have reached your limit. It only a plateau though and to get past this stage takes a bit more time. Then suddenly you are through it and a noticeable difference will gradually start to arise.

Normally takes two years before you get to the stage where the rides become a lot longer and you go looking for hills. From then on things just improve.

Good route for you is up to Falmer on the 23 and then back to Woodingdean over the open fields. When that becomes easy do it in reverse and see what a few slopes early in the ride can do for you. Or longer out to Lewes and back through Cliffe to the 27 and down to Beddingham- Newhaven and then the 259 coast road back home. That is a route I took a few from Shoreham out on and they were not happy as there was a strong headwind back from Newhaven. Choose the route for the wind and enjoy the Road bike.