Quite a number of wildlife gardeners keep a daily diary for their garden.
I'm afraid that I am a bit more intermittent and tend to omit some of the commoner species, although I am a bit more strict with some of the insects that particularly interest me. Basically I just print myself a monthly calendar with plenty of writing space.
Personally, I only include sightings where I have a photograph which is of sufficient quality to enable a clear identification, or species for which there is absolutely no doubt. I must get around to taking some better photos of the overwintering Blackcaps before they move north in a month or two.
There are a number of UK Wildlife ID sites that specialise in garden insects but for a general starter identification book I would recommend Collins Complete Guide to British Wildlife. Not completely comprehensive, as that would require many volumes, but most of the commoner species are included; and even if it doesn't get you to species level it should point you in the right direction.
Recording sites exist for many individual wildlife families but they do require correct identifications, not approximations.
You may find this site useful
http://www.gardensafari.net/english/birds.htm
This link is to the birds page but there are other sections which cover most of the wildlife which can be found in gardens.