Supporting employee mental health needn't be expensive - there's a considerable return on investment, and many measures you can offer are tax free. This one-page briefing from HMRC has information and links to further details.
HM Revenue & Customs
HM Revenue & Customs is the non-ministerial government department that is the UK’s tax, payments and customs authority. It collects the money that pays for the UK’s public services, and helps families and individuals with targeted financial support.