Thanks so much all for your replies. I'm currently on my fourth attempt at HRT for peri in the space of about a year and the one consistent has been that they've all got rid of hot flushes - until they started to reappear at times on Oestrogel.
That said, although hot flushes are annoying, I'm really desperate to try to improve mood swings/sleep/anxiety/concentration issues, so we'll see.
After getting a referral to the menopause clinic I'm now on two pumps of Oestrogel a day, Vagifem and had a Mirena coil fitted two weeks ago to try to avoid the progesterone mood swings that I couldn't cope with (to put it mildly!). It's early days, but no issues so far. *fingers crossed*
Thanks again everyone for replying.