Just a heads up, that if you are able to do your IHT400 and probate forms yourself (and apply for probate online), the whole process for me has taken just 19 days from sending the IHT forms off to receiving the grant of probate. I am amazed.
I was dealing with a large but simple estate (only one beneficiary and everything above the IHT threshold going to charity). The IHT took the most time to complete but the HMRC accompanying guide notes were excellent.
There is hope out there, the long delays of recent years are clearly coming to an end!