Alternatively buy a canal and rivers. trust day pass and bung it it at North Kilworth marina and make your way to Foxton locks,]...
WARNING: depending on the width of your rib you'll want to make it through the tunnel sharpish as we made up for more than half the width so.. IOf we'd met a narrow boat we'd have had to reverse and.. if one came behind... We'd have caused a traffic jam!
Took 2 or 3 hours there and back. and was great fun... Got a lot of admirers and a chance to buy a beer at Foxton
Going in the other direction from North Kilworth you come to a lock... We were too wide. If you're not too wide buy a lock key (Ebay)