The Archive CD Books Project scanned a number of old directories and books and many contained information relevant to Lower Edmonton though perhaps just a few pages out of hundreds on the CD. The scans were pretty good quality though many pages were distorted a little towards the fold. That really isn't a great problem though and they are more than adequate for the purpose they were created for. The CDs I have are Kelly's Directory of Middlesex 1937 which included an alphabetical local trade directory and 1902 Kelly's London Suburban Directory Northern Districts which is sold as a "Post Office directory" and includes uses a street by street local trade directory. Sadly Rod Neep closed down the company in 2007.
A number of directories are available on the Historical Directories site. This used to be a very frustrating site as the search facility wasn't too good and it wasn't possible to browse a directory without starting at the beginning and viewing every single page. There have since been improvements made.
If you want to examine old maps of Lower Edmonton, look no further than The Godfrey Edition of Old Ordnance Survey Maps which are available directly from Alan Godfrey Maps. The maps are published using the survey dates which are 1894 and 1895 but actually say on them Edition 1894-1896 and Second Edition 1896 so they could be referred to as the 1896 maps by others. They are reduced from the 1:2500 series and presented as approximately 15 inches to the mile. The reverse includes local historical notes and extracts from Kelly's Directory. The maps are just about the right size to handle without wanting to fold them. As they are relatively large scale it actually takes six maps to completely cover modern Lower Edmonton, though the last two are really only for completeness to take in the northern boundary.
The Ordnance Survey have an archive of old maps available but they will cost about £25 for pre-1940 ones (and even more for later ones) as they are printed on chart paper and suitable from framing and display rather than being the modern style of fold up maps. They do include 6 inch, 25 inch and even larger town plans though.
As mentioned on the 1867 map page, the Ordnance Survey and Landmark Information have got together to come up with http://www.old–maps.co.uk/ which includes mapping of Lower Edmonton from what it calls the 1881 Middlesex map. I argue that it is really the 1867 map.
There is a very small scale 1786 map that can be glimpsed online. That is on a site where they are selling reproductions of old maps largely for decorative purposes.
As for modern scaled maps, well the best you'll get off the shelf from the Ordnance Survey is 1:25,000 which isn't terribly useful. Anything larger than that and you are into custom mapping and the prices shoot up dramatically.
The London Borough Of Enfield has a Local History Unit, now going by the name of the Enfield Local Studies Library and Archive, that may prove be a useful resource to some of you. They have files of many local papers for example. I haven't been there myself but it has been highly recommended to me. The unit was at Southgate Town Hall but it moved to Enfield Town in a new building that was originally planned to house the library and a museum. Talk in early 2004 was that less ambitious plans for this new building would need to be adopted and this will mean that the unit wouldn't get much more space than it already had, which wasn't a lot at all.