A person can only be made redundant if the need for they type of work that you do has ceased or become less. So it is up to the employer to show that this is the case. From what you have told me it does seem that you are being unfairly selected as there is clearly a need for staff and had they genuinely wished to remove the role of manageress they had a duty to consider whether they could offer an alternative role. As such, I think you should pursue this
My advice is for you to look in your local paper for a solicitor. Many will do a free first interview where your case can be assessed fully which is not possible with this kind of forum.
If there are further points please reply