I can't advise on your PH Registrar ambitions and would suggest transferring this to the medical forum on TSR if someone there can assist?
I can say you have a decision to make
Options
a) Give up and fade away and look for a job a long way away from the toxic environment you are currently working in. The vacancies across the UK at the moment are such you would probably find a new job very quickly. You can hold your head high and still have your sanity. If you are in a 'probationary' period period you may not have many options as this is the time where you and your employer find you are a 'good' fit.
or
b) Stand your ground and go down guns blazing - The circumstances here may be such you could resign and cite constructive dismissal (you are forced to leave your job against your will due to your employers conduct) if you are given unreasonable tasks with an unreasonable time frame. If you decide to fight this, it will be all consuming, it will exhaust you, it will take over your life and you could easily lose five to ten years of your emotional life. You have to be ready to see it through to the bitter end and no be put off by other people who are acting not for you but for the organisation's sole interest. They will want you to drop your complaints as damage to their reputation is wanted like a hole in the head. Use this to your advantage. I don't know how taking such action in your profession (is it a closed shop?) would leave you in the longer term? Maybe someone else can answer that one?
Here is the thing, no one can make this decision for you. Importantly you will not be alone. If you have found yourself unsupported and sidelined and bullied, so will others along side you. The planning and execution of your tactical moves have to be ice cold, calculated and executed with careful planning, with little display of emotion. Your timing and expressing of your discontent and to whom you say this to is crucial, but your limited time with the organisation could limit your options. You need to find out your organisation's grievance policies and see if you want to follow that route - if that is what you want to do. There are some really awful organisations with tiers of toxic management who just want to maintain a status quo, to keep their title and to keep a lid on all things underperforming. If you decide to fight this you have to do it properly and professionally. Where is their evidence that you have not performed effectively? What training have you had to do your role? What are the role profile criteria for your job and are you fulfilling them? You don't have to be part of the gossip squad but it can be helpful to stay on good terms with someone from that group. They will tell you the gossip, and if they don't know it the cleaners will. You need some urgent specialist legal advice (most do 30 mins of free impartial advice)
Evidence. Keep a diary of daily occurrences - and don't make a rushed decision. Keep notes of where you were and who said what, or what happened? Were you left out of meetings, received unwarranted tasks not related to your role, had information withheld, were singled out for criticism etc. Subtle covert bullying is very difficult to prove and to get evidence for. Who did you speak with, who did the communication come from and in what format? Where were you at the time etc etc Keep hard copy records if you can but do nothing illegal. Be careful about the use of recording devices as that can leave you being dismissed without a leg to stand on. Be patient. So get all of your quietly gained evidence at the same time you seek legal advice. That can be exhausting when you are working full time anyway. If you are serious about this you need to do get informed legal advice. Power and knowledge can keep your emotional health intact whilst still giving you options. You can also wind up paranoid because you are sensitised to expecting bad things to happen to you at work (just stay aware of what is reasonable) Don't jump to conclusions or jump in with both feet. Hold your anger in check and sleep on every decision. Speak to absolutely no one at work or elsewhere about your intended plans down the line. Someone will tell all on you. If you say what you intend you will struggle to get the information, you need. If others find out you are quite likely to be deliberately set up to fail.
You need professional legal advice from a specialist employment solicitor. Whilst your Union might not support you they should be able to provide legal aid (usually as part of a package) You need this support and knowledge of what you expect to do as a plan, and the emotional support to know that what you have experienced is wrong.
I do not envy your current position or your frame of mind. Do all you can to find the antidotes from close friends and family. You are never alone even though it may feel like that and work may be so bad. You will always have a choice to do something to change your working conditions. Working as an individual in an unsupported team is soul destroying and it takes a lot of inner resolve and courage to hold onto everything you believe in. Know that you will be a beacon of courage for those other people who are also in this toxic mix. But whether you decide to challenge this or just get out quick that is your decision, your choice and whichever you choose if the right decision for you. Your decisions have to be for you, your circumstances and your life, because the rest of your life is out there.
No work is worth giving yourself a total breakdown. Work is a means to an end. When things get so bad just try and be kind to the person near to you, something you definitely can do. Another place, another time, another team, older wiser and you perhaps will be so happy you will never look back.