With you (OP.) having looked after probate yourself and I right to assume that the solicitor has been engaged solely for the purpose of handling the house sale?
If yes to above this was my experience a few years ago. The Solicitor required that I get the relevant Revenue clearance so that the house sale proceeds could be released to me by her.
I contacted Revenue by telephone and asked about the process. The agent I spoke with was very helpful and between we drafted my request which I sent online through MyAccount.
I guess the same agent then reviewed the SA1 and issued clearance to distribute via MyAccount within a day or two.
I printed it, scanned it to the solicitor, and the funds were then sent to me electronically when all was concluded.
Hope that helps.