Spas near Glasgow for a special treat

It’s my mum’s big birthday soon and I want to get us a special spa day. But worried about turning up somewhere to find it tired or dated or generally crap. Where’s good these days? Happy to travel a bit outside of Glasgow. Would ideally like somewhere we can have a treatment and then hang out leisurely. Maybe have lunch (not so bothered about afternoon tea). Please help me stop going mad googling and give me some real people perspectives 🙏