I had this in my last job. Almost caused me a breakdown and I left as a result.
In fact it sounds SO similar I want to ask and find out if it's the same boss.
Are you in Scotland?
Definitely bullying. I eventually managed to get some proof but unfortunately by the time I got my finances and mh sorted the deadline for doing something about it legally had passed.
My boss would set impossible tasks then claim I'd misheard the deadline (I started getting confirmation in writing by email), would nitpick literally over a full stop in a report - seriously 90 minute rants about punctuation! (Not a publishing job either). When I got wise to how they were things got more sinister. Things going missing inc important files - I started keeping a record of what files I used each day AND got a colleague to witness...
It was at that point when an email was deleted that shouldn't have been (I'd started sending bcc to the colleague that was witnessing my file use), and an important client file that nobody else had any reason to even look at went missing. The email meant that an update of something needed added to the file - that was my job. That same day they made a really nasty snide comment about my disability (thinking there was no witness) which a colleague heard. Colleague took one look at me and said "I'll miss you" I decided right then I would not be back!
In hindsight I could and should have gone over their heads and complained, I had proof and witnesses but I was at breaking point by then. My health was more important.
Probably if I'd been on mn I'd have had excellent advice and support but I had little support and was focused on finances and health.
I later discovered that there was crazy high staff turnover in that dept which the company blatantly lied to me about at the interview (I'd asked how long the previous incumbent had been there & rough reason for leaving - I'd come across issues like this at other jobs and was cautious. I was told previous incumbent had been there 3 years - was actually 4 months - and that they were young and had left to go travelling - they were mid 40's and were working for a rival company in same city).
I hope you're stronger than me. You don't deserve this nobody does. One phrase I did come across trying to find out my rights was
People join good companies and leave bad bosses.
It's so true. Is it a large company? If so hopefully a decent HR dept that can help (although be aware that they are not your friend they're the companies so ultimately their aim is to avoid the company being sued), plus talk to acas (another thing I wish I'd known at the time, I wrongly thought you had to be 'an official' of some kind to talk to them or at least in a union - I now know better). Hopefully they can help you sort out a strategy to get this resolved so you can keep your job without having to put up with this crap!