Try pool work exercises if one is available to you. Water provides 12 times the resistance of air. It also holds you buoyant, therefore no jarring on your lower limb joints. If you can you salt water even better. Looking at a 25 meter pool try the following: 4 laps walking forward making sure you use all the foot with the heel striking first, 4 laps walking backwards, again using the whole foot with the toe striking first. Next the side step for 4 laps. Facing the same way, stride out, plant the foot, then bring the foot in and pause for a moment with both feet together before taking your next step. Change sides and repeat.
At the end of each 4 lap exercise, try these stationary ones. 2 foot calf raise, as you improve use one foot. Remember what you do on one side you must do on the other. Sit on the side of the pool and gently at a pace that you feel comfortable with just swing your feet back and forth with your feet at different angles. When your feeling particularly strong - do circles with your big toes. (Try this at home in front of the TV during commercials now).
Holding onto the side of the pool, stand, balance on one foot and raise the leg sideways as high as it will go, control the ascent and descent at all times. Your physio should be able provide you with more of this styled exercises for the pool. If they can't/won't or don't find another physio. This will help for your lower limb issues. It will also give you the confidence to try other exercises.
Although you may not be in the right age group, but look for seniors exercise programs in your area, often run by your local councils. These program are designed for bodies that have had a few life hiccups.
Once you gained more confidence, try a few of the other Grokker Low Impact. There some really great new ones that also show you modified versions of the exercise being shown at the time. Still if the modifications are too much for you right now just march on the spot using yours arms until you feel that you can join in again. This is the beauty of Grokker, you can do this in the privacy of your own home and you don't need to feel intimidated by other participants if you are not able to do the exercise. You just need the motivation to turn it on. You go girl! All the power to you!