The Liturgical Commission has received a number of enquiries today in the wake of yesterday’s events in Manchester, asking for resources for vigil services. In addition to the prayers tweeted by the Church of England Communications team, by a number of dioceses and by other individuals, the links below to the Church of England website give a number of appropriate prayers for the world/society here https://www.churchofengland.org/prayer-worship/topical-prayers/prayers-for-the-world.aspx.
For those needing a complete order of service, pp. 443–448 of New Patterns for Worship has an outline headed “Facing Pain: a Service of Lament” — also downloadable from here https://churchofengland.org/prayer-worship/worship/texts/newpatterns/sampleservicescontents/npw18.aspx
Some of the ‘Cross’ and ‘Lament’ (possibly also ‘Living in the world’ and ‘Relationships and healing’) resources from New Patterns for Worship might also be appropriate for inclusion in that service, or as stand-alone elements in your regular service.