Uninstall (nearly) everything installed after spacific date

[Bob <spam@homeurl.co.uk>]

Hi,
How can I do this, the way I'd like it to work is
cat /var/log/dpkg.log > ./list
but filtering by date so it only includes packages installed after a 
certain time (grep sed?)

vi ./list
to delete lines for packages you want to keep (running kernel, less, 
hddtemp, whatever...)

pass the ./list file to a command that will beautify it and output 
another list of just package names that you can pass to
apt-get --purge remove

Shouldn't be too hard but my bash is rusty, so I thought I'd ask if 
anyone had done this already before I crack my knuckles and get all man 
bash sed grep on it?

Thanks.