Thanks to the advice from @JinglingHellsBells I had a Dexa scan last week. I'm 53 and have been on HRT for over a year now. I was concerned about my bone density as my mother has severe osteoporosis. My GP wasn't interested in getting me a scan, so I found a private clinic in London and paid £65 to have it done, on a self referral basis.
Really pleased to have a base line now for my bone density and feel like I'm back in charge of my health. Thank you @JinglingHellsBells for your advice on this.