So probably best off using some veroboard/stripboard for the high voltage stuff then.
IC sockets, solder all of the high voltage wiring and the low voltage stuff connected to the stripboard so nothing can come lose or move about.
Sounds sensible, thanks for the advice.
Here's some more advice:
1. You mainly have to worry about current limits when it comes to breadboard; I think they are only suitable up to 1-2 amps.
2. You would only have to worry about the voltages if they were in the several hundred to kilovolt ranges (ie, voltage breakdown of insulation).
3. If you follow proper procedures when working with such circuits, building on a breadboard (provided the circuit doesn't exceed the current and voltage breakdown limits of the board) can be done.
Basically - for number 3 - especially high-voltage and/or high-current designs - you should never touch the board, wires, components, etc while the power is on (it would also be advisable to mount the board on something relatively "immovable" or otherwise secure the board and other components in the DUT (design under test) from movement).
This includes using a multimeter or other measuring instrument "freehand" (if you must do this, use one hand and one probe, and keep the other hand in a pocket - you may still short something out, but it will be "safer"). Ideally, if you need to take measurements or alter the circuit, you power the circuit down (and discharge any large capacitance/caps, if needed), then attach your probes, etc - then re-apply power.
These kinds of "rules of thumb" should actually be something that beginners and experts alike try to always apply, so it becomes a habit, regardless of whether the circuit is high or low power; this way, it becomes and is "second nature" for when a high power circuit is being designed and tested. It would tends to cut down trips to the hospital and/or morgue...