Many thanks for your patience. This appears to be a potential redundancy situation. There are various reasons as to why redundancies may be required, such as economic pressure, changes in the nature of products/services offered, internal reorganisation, workplace relocation, etc. The reason for the proposed redundancies will rarely be challenged and the employer will simply have to justify that the actual reason satisfied the statutory definition of a redundancy.
So in effect they are reducing the need for employees to do the job you are currently doing and are creating new jobs to cover these tasks. It is difficult to challenge this because the employer is free to reorganise its operation as it sees fit. In this case your job is being split into three distinct areas and your employer should offer you these jobs as a suitable alternative employment. When the law says they should offer you these jobs that does not guarantee you will be placed into them and you could be asked to apply and go through a competitive recruitment process.
So from a legal point of view, what they are doing is not ideal for you but can be justified if necessary, so a constructive dismissal claim looks like a difficult thing to pursue in the circumstances. You may be better off trying to negotiate with them and there are ways you can try and do that which I can cover if needed.
This is your basic legal position. I have more detailed advice for you in terms of the negotiating options you have in this case, which I wish to discuss so please take a second to leave a positive rating for the service so far (by selecting 3, 4 or 5 stars) and I can continue with that and answer any further questions you may have. Don’t worry, there is no extra cost and leaving a rating will not close the question and we can continue this discussion. Thank you