Daisy try not to worry.
I would send them a letter recorded delivery quoting the following which is from the DTI website guide to maternity entitlements and responsibilities
'If a redundancy situation arises at any stage during an employee?s maternity leave which means it is not practicable for the employer to continue to employ her under her original contract of employment, she is entitled to be offered (before that contract ends) a suitable alternative vacancy, where one is available. This includes a vacancy with an associated employer or with a successor to the original employer.
The new contract must take effect immediately on the ending of the original one and must be such that:
the work to be done by the employee is both suitable and appropriate for her to do in the circumstances; and
the capacity and place in which she is to be employed and the other terms and conditions of her employment are not substantially less favourable to her than if she had continued to be employed under the original contract.
It is unlawful for an employer to make an employee redundant during ordinary or additional maternity leave period without first complying with these requirements. An employee made redundant in these circumstances will have a claim for unfair dismissal and may also be able to claim sex discrimination. An employee who has been dismissed in this way should appeal against the dismissal as part of the requirement under the Statutory Dispute Resolution Procedures. Failure by employers or employees to use these statutory procedures could result in an increase or reduction to any compensation awarded. The Acas Code of Practice on disciplinary and grievance procedures sets out the statutory dispute resolution procedures that should be followed before an employee may, if the dispute is not resolved, complain to an Employment Tribunal. Employers and employees may also find the general Acas advice on dispute resolution helpful.
If the employer has a suitable alternative vacancy available but fails to offer it to the employee, the redundancy dismissal will be regarded as an unfair dismissal. If the employer offers the employee a suitable alternative vacancy (she is entitled to a four- week trial period in which to decide whether the employment is suitable, and this period may be extended beyond four weeks by written agreement) and she unreasonably refuses it, either before or during the trial period, she may forfeit her right to a redundancy payment. Further guidance on unfair dismissal and redundancy is available from DTI.'
Put that paragraph in and then say -
'as you will note from the above DTI guidance, if there is a suitable vacancy available and it is not offered to me, this constitutes unfair dismissal and possible sex discrimination. As I have raised this matter with you previously and heard nothing I am formally putting you on notice that if I am not offered the suitable vacancy without competition, I will be pursuing this matter as an unfair dismissal claim and will also be discussing with my solicitor the possibility of bringing a claim for sex discrimination.'
The law is clear, this would be unfair dismissal. I would be astonished if they don't back down pretty sharpish if you quote the official guidance at them and notify them that an unfair dismissal claim and sex discrimination claim is on the way.
Try not to panic, just put that in a letter, send it recorded delivery and it should do the trick. Go and see a solicitor as well if you feel it would help you feel less stressed about it, and if you can, but as I say, the law is clear. They may not know it, and may need to look into it, but it's quite quick to find out and is no excuse to leave you hanging and getting stressed.