Cam Belt, Water Pump and Tensioner

[Stuart]

I’m part way through a re commissioning my 928 S4 and the time has come to get the t/belt done
There has been a lot of electrical problems mainly seized pumps and motors to get through not to mention fuel/running problems which are now mostly sorted.
To move onto the next level I really need the car running for longish periods. (still much to do)
Cambelt was a priority from day one but no point in putting money into that until I was sure the car was running at least.
It is now running although this weekend a belt or possibly water pump has started to make a squeal noise (not all the time)
Is that likely an ancillary belt or water pump ?
Mindful of cam belt I've been careful to only start and run on  ticker over and off again 10 mins duration just to warm up  and keep engine lubed each weekend for the past couple months.

Pulleys at bottom end all look fairly dry and slight surface rust. Alternator belt is new and run for about 2 hrs in total.

Car is obviously not yet roadworthy and hoped someone can give me a recommendation on who it could  be trusted to in mid Essex for Cambelt service etc….

Thanks

Stuart

1987 928 S4 Auto