Can anyone recommend a bike shop in Cambridge for repairs to my Klein Attitude (Disc brakes and chainset)? Unfortunately I have no time to do these things myself anymore....

I use Station Cycles in Histon.

Again, +1 from me for Dave at Station Cycles, but do go to the Histon branch. I won't trust the mechanics at the railway station. They focus on more high-end jobs.

For the south of Cambridge, if it's not a specialised job, i.e. if it's something like setting up gears, I go to Blazing Saddles in Cherry Hinton Road. He also focuses on commuting bikes for his day to day job, so he probably won't be able to fix your disc brakes. So that's probably not a good call for what you want to do today.

Pro: The guy there will turn around the job on the same day, and will give you honest advice on whether he thinks you need to spend more money. He will also tell you if he doesn't have the experience or expertise to fix something, as opposed to some other mechanics that will just wing it with a sledgehammer.

Con: He doesn't fix expensive mountain bikes for a living, and probably won't know how to fix up your brakes. (Do they need maintenance, e.g. bleeding, or fixing?) When I took my bike in to have the headset replaced, he wasn't familiar with the sizing, so advised me to go somewhere else. He also can't advise on high end equipment / upgrades, which Dave at Station Cycles loves doing (and seems good at). But he was great with increasing the tension on my wheel spokes, setting up gears on both my road bike and mountain bike, etc.

Yes, Dave at Histon seems to know his stuff

Many thanks for all of your advice