Seeing as you are all so interested here's how it went.
40% raw wheat
10% oat malt
I usually get 75% efficiency but have never managed to achieve that with wheat. Went for 65 and in the finish got 60% - i'm okay with this.
Decided not to bother with the cereal mash. And the starches gelatinized just fine.
Beta glucan rest 113F for 20 mins in the bk. 1.8l/kg
Raised to 150 over low heat (stirring this was alot of work, a very heavy mash). It took about 25 mins to raise the temp so I guess the mash got a protien rest aswell
Added 150F mash to mash tun with 5.5L of liquor at 150F. Used the liquor to preheat the mash tun. 2.6l/kg
Sacc rest at 150F for 45 mins.
Checked starch conversion at 30 mins and it was complete, but left it for 45 as mash out liquor wasn't ready anyway
7L mash out at boiling
Mash lautered like a dream - no dramas at all. I use a copper manifold with slots cut in it so was expecting some trouble. The grain that was left in the mash tun was like a solid brick with a thick layer of grey protien on top. Yum.
The result is 20 litres of white/yellow cloudy wort, just like I hoped.
So what to take away from this?
The beta glucan rest really seemed to help. I also feel the mash out had its part to play. When the temp came up to 168F the mash was quite fluid.