Assuming you are located in the UK, then the first book on your shopping list should be WildGuides’ Britain’s Spiders by Lawrence Bee, Geoff Oxford and Helen Smith which was published in 2017. It covers all of the British fauna excluding the majority of the money spiders (Linyphiidae).
If you would like a reference to enable ID of mature specimens from palpal strucure or female epigyne, then there are a number of older books that serve this purpose although Collins Field Guide to the Spiders of Britain and Northern Europe by Michael Roberts is the cheapest and easiest to find.
Good quality hand lens can be found online from entomological suppliers such as NHBS, Watkins & Doncaster, Anglian Lepidopterist Supplies etc., although there are some surprisingly good lenses withbuildin LED lights available on eBay for under £10. Something offering 10x magnification is ideal.
Hope this helps.