Peter
I too just had between a third and half of my tongue removed and wrist tissue put into its place. With the trach tube in, speech very difficult in hospital. Once out though, I had very good results with speech therapy - going from no voice to unintelligible noises to understandable "stroke speech" (you know, like Dick Clark sounds on New Year's Eve the last three years ). the worse part is the phone since they can't see your lips. Plus phone voice recognition systems are hell ("sorry , we did not understand what you said, was that appointments or payments?")
Sadly, I have to start all over again as the CyberKnife radiation burned my tongue and it has swelled up. The key is to get a good speech therapist with some experience with tongue cancer patients
As for consonants: big time trouble at first with k-k-k-k-k and g-g-g-g-g sounds (eg bark gag ) technical names: lingua-velars.
Once those are down, then onto lingua dentals (th) lingua alveola (t, d, l,s, z) lingua palatas (sh, ch)
I was also promised "big success" but it turns out our definitions were different. They mean you can talk slowly and people will understand you - but you still sound like you had a stroke. In comparision with not being able to swallow though, then yes, speech therapy was a big success . This next time around I am going to try VelaStim electric stimulation as recommended to me by one poster for swallowing and speech therapy.
Good luck - be patient
Charm