Look at CPC before RS, Farnell and Digikey unless money is no object. CPC are part of Farnell but you can often find the exact same parts cheaper at CPC.

Cable trunking is the normal solution. https://cpc.farnell.com/c/cable-lead...-slot-trunking

Cable tie bases are available in self adhesive or screw fixing. https://cpc.farnell.com/c/cable-lead...ble-tie-mounts