Training around Belgium...
The best place I’ve found for doing consistent paced efforts are the canal roads of Belgium. they are long enough that you can do easily 30 minute steady TT work without ever once having to stop.
There are hills in Belgium (contrary to popular legend) and you can find them in West Flanders in the region of Iper and in the East Flanders area just to the south of Oudenaarde. With a little planning and some route following you can make some hard-power rides to help give you that extra little kick in the races you might be lacking.
Belgium is also home to some long slow 5k climbs in the Ardeens region of Belgium. It’s quite possible to reach this area via train (you will have to pay to bring your bike on board). Lille and Spa are some good places to start from. Be sure to check out the courses of Liege-Baston-Liege and La Fleche Wallonne to help you find the best climbs in the area.