Firstly, most HRT preparations have bio identical oestrogen apart from Prempac/premique (which is equine sourced) - so the others will be as natural as you can get. You have two options for progesterone if you want to have bio identical or, at least, close to bio identical.
Utrogestan is the try bio identical and suits many women however it does need to be taken on an empty stomach (which can be a nuisance) and can make you feel slightly sedated. You take Utrogestan either sequentially or continuously and use oestrogen separately in either pill, patch or gel form.
The alternative, which you may find the most convenient to start with, is Femoston which comes as pills. The progesterone is close to bio identical so is very popular. There are sequi and conti versions and it seems to suit many women very well.
Even if you are post meno - so haven't had a period for over 2 years - I would still start by using a sequential form of HRT which results in a monthly withdrawal bleed to protect the uterus as it gives you a better chance to gage whether the progesterone suits you.
Do check out the HRT Preparations section on this site to get really clued up.
Keep us posted. DG x