I recently heard a high pitch noise from front RH side and called the AA. Diagnosis was power steering fluid leak. The AA won't pay for repairs saying it was long standing leak yet it was sudden when it happened. I have home start and breakdown repair cover with them. Can anyone advise.

It sounds like its time to get it booked in for a look. Could be a lose hose ? or more like the power steering pump, assuming for some reason its not lower down and the rack.

A seal can easily pop on the rack due to grit or wear and tear.

Is it a 1.6 petrol mk2 focus per chance?

Same problem with mine, there is a metal pipe coming off of the power steering pump (on the front) it is a high pressure line with pushes into the compression nut. The seals often go on Foci and need changing. Nasty business is the pipe cannot be removed with damaging it. Easy way to check is to start the engine and then look for a leak from the connection into the pipe. I took mine to a garage and they charged me £180 for the work which covers £15 for the nut, £80 for the high pressure line, steering fluid and labour, so not bad considering its a pain to fix (even after taking out the alternator for better access).