You can certainly get WW1 records from ancestry UK but it is another pay site I have used Ancestry for a long time and it works for me. Unfortunately for all sites some WW1 records where lost during a bombing raid and subsequent fire/water damage. I have managed to get my paternal grandfathers info but not my maternal grandfathers. I have also got info from a great uncle that served with the Canadian Forces from the same site.
Hope this is of assistance if you need a hand quite happy to help with what bit i know.Not to far from each other.
Keith