There are two modern identification guides for our species; both by A.D. (Tony) Barber and obtainable from FSC Publications.
Key to the identification of British centipedes ~ AIDGAP key (2008)
Centipedes ~ Linnean Society Synopsis (New Series) 58 (2009)
The older standard work, from which the above derive much of their information is Centipedes of the British Isles by E.H.Eason, published by Warne (1964) has been long out of print. Though some of the nomenclature has since changed, the original species descriptions, illustrations and details of distribution remain invaluable.The 'Synopsis' provides a more detailed account of each species and is suitable for more experienced users.
The only available key to millipedes is the 1985 Synopsis of the British Fauna No. 35 by J. Gordon Blower published by The Linnean Society and Brill/Backhuys. Sadly it is out of print, but it may be possible to obtain copies through specialist entomological book sellers or online sellers of second hand books.
A revised key is being prepared by Paul Lee, and draft versions may be made availble.
Two main publications for the identification of woodlice of Britain and Ireland are readily available from FSC Publications.
A key to the woodlice of Britain and Ireland ~ FSC AIDGAP key (1991)
The Field Studies Council AIDGAP key by Steve Hopkin is widely regarded as better for living woodlice or fresh material. It contains keys to the 35 species of woodlice known to be native or naturalised in the British Isles.
Colour plates support detailed line drawings and confirmatory descriptions of each species include notes on distribution and natural history.
Woodlice ~ Linnean Society Synopsis (New Series) 49 (1993)
The Linnean Society Synopsis by Oliver & Meechan provides a detailed account of all 38 species which were known up to date of publication. It is suitable for more experienced users and particularly helpful for preserved specimens.
Waterlouse (Water Slater) Identification
A key to the four species of water-slater in Britain and Ireland is included in:
Gledhill, A.T., Sutcliffe, D.W. & Williams, W.D. (1993). British freshwater Crustacea Malacostraca: a key with ecological notes. Freshwater Biological Association Scientific Publication No 52.
Available from FBA website.