I had heard (but not seen or verified for myself) that the London canal system is becoming clogged with "liveaboards" in the style of new age travellors in old barges covered in tarpaulins and junk, hence my comment that Little Venice could be like Little Jaywick. I would check it out if I was you as the comments I had heard implied it was not a pleasant experience.
As Betty says, London is a through trip, not a stopping one. Nice to see the sights from the river as you pass through but no-where to really stop. I would have scheduled it for a single day event.
Once on the non-tidal thames then be aware that distances are very deceptive. Windsor, whilst you could get there in a day from Teddington (where the Thames becomes non-tidal) it is really two days of slightly less frenetic travel ,you have Hampton Court on the way, Thorpe Park (bus ride), Runneymede. James has done some delivery and collection trips over similar distances in a day but that was with two drivers and continous motoring. Once in Windsor you can get to Legoland by bus.
I would have been inclined to look at using the car and trailer to drop in and out of the Thames to get the best. Perhaps Gallions Point for a couple of days with a boat trip through the centre and staying at Gallions perhaps for a DLR train trip into London itself for some sight seeing. Note that you have to like aeroplanes at Gallions Point.
Then perhaps come up to Windsor (MDL has a good slipway) and do a couple of days there.
August 19th-21st, Henley-on-Thames, is the 80's Rewind Festival if you fancy a music festival on the river (we will be there!) However mooring becomes more of a challenge.
Martin



