I've been walking out the shores around london for just over a year now, for what its worth, here's some ideas!
Fanshawe Park (Fanshaw lake) just off of Clarke Road is $5.00. The top side of the dam and along to the south east shore, by the rowing club is consistent for 1-2 lb bass, and pike. Its a nice shore walk but can be busy.
The Thames river is good throughout the city but with 10 miles of river to fish I have yet to find one area that is any more productive then just picking a nice spot and throwing a line.
The North and South ponds in the south end of the city, just off of Pond Mills Road can provide some fun for and hour or two for small bass and pike.
A short drive West of the city is a small town called Komoka. Old quaries are all over and some are stacked with bass up to 4-5 lbs. A small provincial trail just south on Komoka Rd and Glendon Dr, provides limited shore access to two ponds, watch the signs as most of the ponds are on private property and cannot be fished!
Hope this helps make your stay a little more enjoyable! Enjoy the area!