Contract Advice

Hi, I'm an animator and I've been given a new contract, and wondered if anyone who's more legally minded would mind checking it out for me.

There are a couple of points I'm unsure about. First, I have done 5 jobs for this company without a contract. Does this contract apply to those jobs, or only jobs I complete going forwards?
Second, it says they are under no obligation to credit me with authorship. This is a deal breaker for me, as the jobs are very low paid, and the only reason to do them is if I can use them to promote myself.

Here's the contract:

Terms and Conditions: Creating content with ### THIS AGREEMENT is made on 19/04/2017

BETWEEN:
(1) ### (“Publisher”); and
(2) ### (the “Filmmaker”).

Term Sheet:

1. Rights and Ownership
This Agreement shall be governed by and construed in accordance with the laws of England and Wales and the parties hereby submit to the exclusive jurisdiction of the courts of England and Wales.
a) The parties agree that the commissioned Work done by the Filmmaker pursuant to this Agreement shall be deemed "work for hire" under Copyright laws of England and Wales and the Publisher shall own the Work and shall be the full and exclusive owner of all rights and title in and to the proceeds of the services commissioned herein at all stages of development, including any ideas, discoveries, designs or products developed.
b) If for any reason the Work or part thereof is not deemed a work for hire, then the Filmmaker hereby irrevocably transfers and assigns to the Publisher in perpetuity, all rights, title and interest therein including all copyrights and any other applicable intellectual property rights.
c) The Filmmaker shall not do anything or cause anything to be done to limit or infringe the Publisher’s rights under this Agreement and undertakes to execute any document required by the Filmmaker to secure the Publisher’s rights in the Work.
d) The Filmmaker waives all moral rights in the Work and the Publisher may make any changes or additions to the Work at their sole and absolute discretion, is under no obligation to use the Work or to credit the Filmmaker with authorship in the Work or part thereof.

3. Content Indemnification
All content created by Filmmaker is either original and where applicable, the Filmmaker has the rights or licenses or other permissions required to execute the Work with agreements in hand confirming appropriate rights to all intellectual property involved. Filmmaker may use the work itself solely for a virtual portfolio or on self-promotion channels, limited to a 30 second clip of the Work. Filmmaker may not publish content on YouTube.

4. Relationship of Parties
Filmmaker indemnifies Publisher against any issues related to intellectual property rights and guarantees that the Work will not infringe upon or violate the copyright or intellectual property rights of any other person, entity or third party. Publisher acquires all rights to the Work and may use, modify, distribute, sublicense and monetize the work in any medium, in any geographical location, in perpetuity. Publisher agrees that
It is understood and agreed by both parties that this Agreement does not create or establish an employment relationship. The Filmmaker shall operate as a self-employed independent contractor and shall assume all risks, expenses, insurance coverage incurred in providing work or services under this Agreement. The Filmmaker shall not be entitled to any rights or benefits provided to the Publisher’s employees. The Filmmaker may provide similar services to a third party. The parties agree to provide relevant documentation required for financial reports and taxes.

Thanks