I’m pretty sure tibolone is widely available (I hope so - I’ve been taking it 6 months myself and I agree it’s brilliant)
I think many medics are wary of prescribing it because it’s a synthetic steroid taken orally and therefore considered old fashioned.
My own GP told me the practice always prescribes patches, gel etc as a first-line HRT and only prescribes tibolone if it's recommended by a consultant gynaecologist, as it was in my case (I was prescribed it by the hospital following investigations for bleeding on regular HRT).
Like bombsh3ll says you can buy it privately, though you shouldn’t have to, if it works best for you and you have no health contraindications.
Re other HRT in oral form, there is Bijuve, which is a bioidentical combined oestrogen-progesterone that’s taken as a daily pill. But that’s all I know about it.