So I've got an orange "!" light that's on the dash along with the message "Power Steering Malfunction".

Steering therefore is slightly tougher, but not much.

What's the likely issue here? Is it recommended I locate the sensor and give it a clean (if that is even doable for a novice like myself) or is it pretty much nailed on that I need to get it looked at and fork out more money (given I have had a brake switch sensor replaced and the turbo pipe replaced in the last few weeks)!

Thanks in advance for you wise and helpful words....

May be helpful to get hold of a code reader and see if any of the DTC's give you some more information. Check the fluid level also, and have a look to check if there are any fluid leaks etc.

Though I'm not certain if low fluid even throws up a fault light - my first ST dumped most of the PAS fluid out when a pipe came undone, no warning light came on at teh time.