The most common (possibly only?) useful split I ever saw as 5 years as a GA conductor was Ipswich - Manningtree, Manningtree - London.
Doesn't always work so check carefully and be very careful on evening trains, a fair few London - Ipswich (Norwich) services skip Manningtree in the evening.
I use that one when visiting family in Ipswich at short notice if I can't find suitable advances. I think it only works because of the Network Railcard discount which only applies London to Manningtree. (As an aside when I tried putting London-Ipswich into trainsplit last year - I haven't tried the new version - it didn't give me any splits at all). Of course that won't work to arrive at 0900.
Trainsplit does identify "splits" for Network Railcard holders at Manningtree (or, for non-stop trains, at Colchester) at times when the Network Railcard is valid. Of course this is only times when Network Railcard discounts are available (so does not help the OP), and not when using Advance fares....the Network Railcard discount which only applies London to Manningtree. (As an aside when I tried putting London-Ipswich into trainsplit last year - I haven't tried the new version - it didn't give me any splits at all). Of course that won't work to arrive at 0900.