In reply to Robynbobbin: I really feel for you here, because I've been screwed by two employers before, once I pursued tribunal proceedings and they settled before it got there (I won). The second time I couldn't be bothered with the hassle, so even though I knew I had grounds, didn't want to pursue it because it's a bit unpleasant and so on.
Thing is - I WISH I HAD NOW!
If this thing gets sour and you think you're getting screwed or they do actually screw you over, my advice to you would be to pursue it.
One thing you've got to bear in mind is that MOST employers know that the employee has the power to get them back if they don't follow the law. So if they've got any sense, they will tread carefully.
To quote from the bbc site, regarding unfair dismissal.
"There is also an indirect form of dismissal that could lead to a claim, and this happens when an employer treats the employee in a way that means they can't do their job. An employer could make the employee's life very difficult by changing their terms or conditions without consultation, or changing the job location at short notice, or accusing an employee of being incapable of carrying out the job.
If the employer's actions amount to a fundamental breach of contract, the employee can resign and claim constructive dismissal."
From:
http://www.bbc.co.uk/crime/law/unfairdismissal.shtml
There is alot of information on the internet if you look for it btw.
I'm no professional and my advice would be to seek some qualified advice but here's my two penny's worth.
From the information you've given, it sounds like they are bordering on constructive dismissal. You need to wait and see what they say on Monday. Either way, if they want to fire you, they have to have a reason. As far as I understand it, they can't force you to resign! If they put in a position where you think you have no choice but to resign you might be able to resign and claim constructive dismissal. If they fire you and you think it's unfair and/or they haven't followed proper procedure, told you what they think you need to improve on and given you chance to improve it etc, then you may have grounds for unfair dismissal.
Do some trawling on the internet.
Also, if you have it, have a look through your company's grievance procedure and also their discipliniary procedure.
Probably my biggest piece of advice is FOLLOW YOUR GRIEVANCE PROCEDURE. If they screw you over you will have a MUCH stronger case if you have followed the grievance procedure (you may not have a case at all if you don't). This will usually take the form of first discussing your concerns/grievance verbally with your line manager. If still no joy, you put your grievances into writing to your line manager. They are then obligated to look into and reply to you in writing. If still no joy you put your grievances into writing to the next senior person from your line manager.
Employment law is very complicated but you should be able to get some good professional advice from somewhere.