Adam - top one isn't olivalis. It looks like a washed out Pyrausta aurata, but that's much smaller than olivalis. Second one - if it is the right size and colour for postvittana that's what it is. They are very variable.
Mark - Small Square-spot. Square-spot Rustic is never that rich colour and doesn't fly until August. You might want to remove those slugs - the big ones are predatory.
Keith - could be but looks more like worn arenella.