Aside from anything else, you need to be very careful of passers by. You will be concentrating on the fishing, next thing a jogger or cyclist has a fly in thier mush.
Forget the other side of the canal for now, work with the nearside, I had a nice perch 8ft from the end of my rod the other week.
I am lucky to have a reasonable length garden I can practice in. If you dont have space I would suggest you get somewhere and practice a stance and cast that lets you work the near bank, without risking passers by. You basically stand at 45 deg to the water, and hold the rod over the water at about 45 degrees from the horizontal. Run a piece of string to represent the edge, and practice not going over it.
Casting instructors will shoot me down in flames for suggesting this but it works for me, and you will find if you can a reasonable distance like this, the more traditional stance for casting will come easier. I can get a pike fly 20 yds down the bank like this without the fly coming over onto the towpath. Not great distances by any stretch, but its safe. ( ish

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One piece of advice I read on here that served me well is don't try and go too far at once. This is a bit tricky as you need to be a reasonable distance to load the rod, but if you try and get too far without any practice you will end up in a mess.
Also, try overlining by 1. It doesnt half let you know when the rod is loaded, and will help get more line out sooner. Mill ends are £4 at mullarkeys, great for finding your feet with.