Hi Chatee, the relevant parts of the SEN Code of Practice for this situation are below. As you will see, you have no right to get a 'proposed ammended statement', only a copy of the 'ammended Final Statement', following that a right of appeal.
So, basically, the LA are following procedure, but they have missed a bit out.
They have read the annual review document, and are informing you that they need additional advice.
I would say that you need to write to them, and say that Pararaph 8:128 of the SEN COP states that they must (it is a legal distinction, so very important) explain the reasons for the proposal and ensure that the parents have copies of any evidence that prompted the proposal.
As they are seeking the advice of xx, xx, and xx, you would expect that they send you further details of their proposed changes once they have received the documents and decided what they wish to ammend.
I personally would also say that until they have received those, and decided on the ammendments in full, you would not consider to have been properly served notice under the terms of the Code. Therefore, you reject this notice as proper Notice under the terms of the Code, and will await their proper Notice once they are in posession of all the facts that they are likely to base the ammendment on.
But, as always, I am just a lay person reading the SEN COP. I am not an education lawyer, nor am I a tribunal's expert. Just a Mum who reads 
If you haven't got a copy of the review report and the school's recommendations, you need to ask that you are also given these.
"8:128 For amendments following a review, other than after a reassessment, LEAs must send the
parents an amendment notice that sets out the details of their proposed amendments.
The amendment notice should be appended to the Notice to Parents set out at Part B of
Schedule 1 at Annex A. They must explain the reasons for the proposal and ensure that the
parents have copies of any evidence that prompted the proposal. Where a proposal to
amend the statement arises from the annual review, the parents should have already
received copies of the review report and the school?s recommendations.
8:129 The LEA must consider any representations made by the parents before deciding whether
and how to amend the statement. If the authority concludes that an amendment should
be made, they must make that amendment within eight weeks of sending the amendment
notice to the parents. If the LEA decides not to go ahead with the amendment, they
should write to the parents explaining why, again within eight weeks of the original letter
setting out the proposal to make an amendment.
8:132 When a child is moving to a new school, particularly at phase transfer, the statement
should be amended to name in Part 4 both the current placement and the new
placement, stating an appropriate start date for the latter. This will make sure that
parents, children and the receiving school can plan well in advance of transfer, and entitle
parents to appeal to the SEN Tribunal in good time if they disagree with the named
school. At phase transfers, except from early education settings to the primary phase,
the statement must be amended no later than 15th February in the year of transfer. The
amended statement should specify the current school attended by the child (if any) and
the new school, indicating the date on which the child will move there.
8:133 When the amended statement is issued parents must be informed of their right of appeal
to the Tribunal against Parts 2, 3 and 4 of the statement and the time limits within which
they should appeal, the availability of parent partnership and disagreement resolution
services, and the fact that the parent?s right of appeal cannot be affected by any
disagreement resolution procedure."