I am a union rep in my workplace and I think YABU as from your OP it doesnt seem like you understand what our role is.
I am not a trained lawyer (I have a degree in the field of criminal justice which helps with the basics but is irrelevant to my actual job role and not a requirement) nor is a workplace grievance the same as a legal trial. As part of my union initial training we get a 10 day course which includes covering the basics of employment law and ACAS codes of practice but it is not in depth or any form of real legal training.
It is also a voluntary role - I get paid leave for union training and if I am asked to attend meetings/hearings during my working hours then I am paid, but anything else is 100% unpaid. I will always try to support my colleagues as much as possible for meetings, but I have my own work and personal life, and at any ne time you may not be the only person she is supporting in your workplace.
Where I work there are 500 staff and 290 are members of my union. I am currently the only shop steward (there was another but they retired in January and we havent yet found anyone else willing to step up) and just at this moment in time I have 6 different workers who have individual cases I am working on, as well as the general support I am offering to colleagues with regard to the covid 19 situation - we work retail so the laws/policies about CEV/shielding/time off/H&S reporting etc are constantly changing so I have to keep my colleagues updated almost on a daily basis. I cannot and will not spend all of my spare time on just one colleague.
We are not there as any form of legal representation. We are there to support a worker and to ensure that employment law and company policies are followed.
She read all my case and said it was very good but not at one time did any research, offered up any similar cases, everything she said was 'in my opinion' and 'I would have thought', no concrete facts which surely a Union Rep should be seeking and providing.
Why do you think your rep should be doing any kind of research? It is your responsibility to do that - beyond the research into specific legislation.
Similar cases will be irrelevant- workplace grievances are not courts of law and so will be very unlikely to be of use, unless the circumstances are identical, as it can be the smallest of differences that can change the outcome of grievance hearings (eg I had two colleagues who failed an internal age restricted sale test in the space of 2 weeks - one had no action taken and the other was given a final warning and had their annual bonus suspended. The difference in consequence literally came down to the fact that there were 2 signatures missing from paperwork in the first colleague's training file)
Additionally, because we are not legally trained we are not allowed to give legal advice and therefore we have to caveat any advice as being in our opinion/experience or "as far as we can see". If we make concrete claims that are either untrue or not upheld, then that is far more detrimental. We can, and do, look for laws/policies to support your case but cannot give legal advice.
It just seems a poor service with little input. I've spent hours researching my issue and feel alone in this. I've had to initiate any meetings with her and emails with specific questions have gone unanswered.
It is not a service you hire to "take your case" and you turn up and sit there while we take the lead - you are responsible for the content of your case, we are there to provide support, advice and guidance to relevant information/policy/legislation that can help when requested.
The non response to emails is not acceptable, but it is not on your rep to be proactive in contacting you, that is your responsibility (personally, if I'm involved in a case then I will try to make a point of checking in with the colleague between each official stage, but if they want a meeting or to go over their case in detail, it is on them to request that and I will try to make time for that)