Trains on the 16th are running from Manchester/Stockport through to Euston throughout the day, with 2 trains an hour instead of 3. Looks like journey time is 20 minutes longer than normal for possible works as they may be using slow lines on approaches into London. But no need to go via any other route. If you have a normal Saver ticket – then you can go via Sheffield but this will take much longer than the direct service to Euston.
Routing via Doncaster would not be permitted (and is even longer).
Other option is take to Cross Country to Reading and then get a train into Paddington – but this is very slow. Or change at Leamington Spa and get train into Marylebone.
However – I’d just take the direct service that they are offering