@Kate62 I live in SA so cant help you with any exercise classes near Logan but if you wanted to do something by yourself in the comfort of your own home.......yes, you will have to motivate yourself....then can I suggest the Pilates DVD that is available via the link below.
www.bcna.org.au/news/2011/12/strengthen-your-recovery-a-pilates-dvd/Information about Strengthen your Recovery: A Pilates program following breast cancer surgery is available through BCNA's website: www.bcna.org.au or by calling BCNA on 1800 500 258.A free "care parcel" inc the DVD, bra, pillow & assortment of brochures, were given to me while in hospital before my surgery. if you didnt get one then you could order one for free via the details above. Even though my surgery was Dec 2017, I still do the DVD exercises 5 times a week after I return from my morning run or walk. It keeps my body flexible & loose & especially helps with the tightness you may feel following radiation. the program is designed for up to 10 weeks after surgery so I just continue to do the "10 week on" session.
I am a bit of an exercise nut so i also run & walk as well as making up my own strength training session using hand weights or just use jars or anything with a bit of weight. This helps with bone density.
Hope this helps. It isnt the same as the fun you can have in a class environment getting the motivation & friendship of others but sometimes it is nice to do something free at home when you want to.
All the best & I hope you find something that suits your needs so you can get out & enjoy all the benefits of exercise!!
take care xx