What do EU pilots use for IFR enroute charting (besides Jeppesen)?
In Europe, like in most of the world, IFR enroute charts are published in ENR 6 of the national AIP, which can be found notably from Eurocontrol @IS online. Some countries publish these charts in sections ENR 3.x.
Some countries like Spain even publish electronic charts.
More details (route data tables) about IFR routes are published in the following sections:

ENR 3.1 Lower ATS routes
ENR 3.2 Upper ATS routes
ENR 3.3 Area navigation (RNAV) routes
ENR 3.4 Helicopter routes

Note: this organisation of routes will change soon.
There are numerous companies offering flight manuals beside Jeppesen and Lido: Navblue is one example.