Welcome to the forum Simon, you'll find the members on here are a friendly and helpful bunch 🙂
do you know if your power steering is elecric or hydraulic? This should be in the manual. If it's electric I'm wondering if it's worth getting the battery tested as a lot if electrical issue ls can be traced back to a failing battery. If it's hydraulic, have you checked the fluid level? A leak would obviously affect nthe steering.
if it's not that, have you hit anything recently? Pot hole, animal etc which could have knocked out the tracking or bent a track rod etc?
cheers
Steve