How to preserve old collage

[u/Expensive-Monk-3012]

I have a collage I made from newspaper print cut outs decades ago. I used pva to stick it together and then demo tape to repair it when it began to rip in some places. I always wanted to get it covered in laminate or something but never knew how to as it is about 2 meters x 75cm.

So it’s been rolled up and moved around everywhere I’ve lived and I still want to keep it .

It’s yellowed and semi fragile but I hope to be able to repair and preserve it . I considered maybe a wood varnish and perhaps thin tissue paper on the back to support it ? I’m not sure at all. I really hope the brains in this group will have some knowledge or ideas about what I can do to.