That’s poor of the NHS not to offer you physio, as soon as my cast came off I was referred but chose to use my work health insurance and go private. Mine is based in a sports center and gym which has been great for learning what I can do – I use the TRX machines a fair bit as it helps support my weight.
One thing my physio encouraged was balancing on my bad leg as much as possible. I started doing it when I was brushing my teeth, fingers touching the basin so I wasn’t too wobbly and just holding it as long as I could. In 2 weeks I built up from 6 seconds to over a minute, just doing that, could be worth a try? The other thing my Physio said was very important is a wobble board. Use it every day – she said this at least twenty times every visit! Proprioception!