Varnishing a gouache on paper

Hello,
I have a 136 x 231 cm. gouache on paper, for which I used Lefranc & Bourgeois Linel Gouache, diluted with distilled water. The paper is Artistico Fabriano 300gr/mp. I applied on it, by brush, 3 layers of Fixative for tempera and watercolor from Bresciani / RestaurArte. It is recommended that this product be applied in 2 to 3 layers. It is based on polyvinyl acetate. It contains ketonic resin, alcohol and glycolic ether.
I want to protect this work in the best possible way. Would it be advisable to continue adding 1 layer of Golden Isolation Coat and 1 final layer of Winsor & Newton Professional Acrylic Matt UV Varnish? Furthermore, would it be advisable to apply one layer of Isolation Coat also on the back of the work?
I have access to these products. Would any other products be preferable to achieve better protection?
Thank you!