Virgin West Coast Advance availability during engineering works ?

[General Zod]

I have to be in Glasgow on the afternoon of Saturday 28th July. Unfortunately, the National Rail Enquiries website states that the line between Glasgow and Motherwell will be closed on the 28th and 29th of July. If this is the case what will be the possibility of Advances being sold between Birmingham New St / London Euston to Glasgow Central ? The Euston to Glasgow via New St services are being terminated at Carlisle whilst the Euston to Glasgow via Trent Valley will be diverted via Mount Florida. I am booked on a Glasgow Queen St. to Oban train which is due to depart 1637 and obviously want to arrive into Glasgow with plenty of time to allow me to get across to Queen St. station.