I was as well doing 1 lesson a week for about a year, half of them got cancelled due to for circuits it needs to be near perfect.
If a lesson is cancelled use it wisely and revise for your airlaw and other 5 exams. Alternative stick with it and as your self employeed be generious on your time, maybe when a good week of weather is in sight try to book as much flying as possible, do it after work ect??