So basically what you want to do is utilise gravity to help the baby into the right position (which is head down, turned (with their back) slightly turned towards your left hand side) - which is why, if you can sleep on your left side that's good too. This is the best position as the baby has to do less rotation to get the shoulders out when he or she is being born.
Reduce/stop any sitting back lolling on the sofa or other types of sitting of this nature as this puts you into a position which only encourages continued breech or movement towards a spine to spine positions where instead of the back of the head sliding under your public bone and the neck being easily flexed as they pass through, they're facing the totally opposite way (and you have a painful backachey lavour). Instead, sit backwards on a dining chair, sit upright on a beanbag - whatever, sit upright/upright and leaning slightly forward wherever possible.
Activities like on all fours scrubbing your floors is absolutely of benefit (although you don't have to do the floors if you don't want) and getting some cushions/blankets on the floor and watch TV for a bit with your head down/ass high as this can help the baby have opportunity to drop towards your diaphragm and out from the pelvis where there bottom half is currently sitting.
Try the yoga position Cat - www.wikihow.com/Do-the-Cat-Pose-in-Yoga - after step five, drop your elbows and go head down/ass high for a bit then repeat a couple of times.
If you get to labour and baby still hasn't turned it's not the end of any opportunities for baby to turn. Doing plenty of head down/ass high WITH the contractions can be really helpful. So there is a lot you can try.
I would also say, when you get into hospital they will of course want you to have 15 minutes continuous electronic foetal monitoring most likely, lying down. You can say great, I'll kneel on the bed for that bit I'd rather not lie down - because doing it kneeling won't affect them being able to do the monitoring. But lying down is generally the absolute worst position for you to get in (not only for breech reasons but it can contribute to babies having Type II heartrate dips as labour progresses). After that monitoring is done, walking about, kneeling, rotating on a birthing ball could all help to turn the baby with the help of those blessed contractions!
There are also some ob consultants who will turn a baby through external manipulation - read up on it to see what you think. Obviously you'd only want someone to do that for you if it was within their practice ie they were a consultant who knew how to do it, had done it a lot - different consultants, different midwives develop skills within their area of practice so will have different skillsets to each other.
Hope that's helpful (and I am a Yoga for Pregnancy and Active Birth teacher so I have done a fair bit of training in this area).