Thank you of your question. You do not say if they have followed their own disciplinary procedures but suggested they have not done so. Normally when there is some allegation then the first thing the employer should do is investigate and you should be included in the investigation so that you can explain your point of view. Secondly they should do the investigation as expeditiously as possible particularly where you are suspended. You are also entailed to to be given reasonable notice of the disciplinary meeting and of the allegations so that you can be properly prepared. It sounds as if they have done none of those things .

You should certainly attend the meeting and you should raise issue with the way the matter has been dealt with. You are entailed to be accompanied at the meeting by a union official or a work colleague and you should exercise that right if possible. You should make the point that you have been denied proper access to your laptop to prepare your response and make sure all of those points are recorded and minuted . You should keep independent notes anyway . If you are then subject to disciplinary action you should appeal. If all of that is unsuccessful then certainly you may have a claim for unfair dismissal but you must not resign and claim constructive dismissal - that is very difficult to establish and the mere fact that they have not followed the proper disciplinary process is unlikely to be enough if you resign before they have decided whether actually to discipline you . You are better off to go through the process and make sure you record the bad practice and then claim if you are dismissed.

Bear in mind that even if you resign there is no guarantee they will not give you a bad reference which could affect your future prospects. If you can show they are not acting properly they might agree some sort of compromise with you so that you can leave and get a reference.