My understanding is because of high moisture content willow needs 2 years storage before burning. so you need to build this into your plans.
There wasn't much heat in the couple of tonnes of willow we used on the multi fuel burner .. same applied to the poplar. we were forever having to feed the stove with it.
The resinous well dried ex Leylandi
caused a lot of tar but gave a lot more heat .
Hawthorn is also good but it spits hot embers every where so a good fire prevention practice & fire guard is essential .
Apple wood & power washed off root logs was the wood that gave us about the best out put but one evening there must have been a stone in a bit of root for when it got very very hot it exploded it & knocked out a couple of strips of the Pyrex type glass in the door
Somewhere on the internet I've seen is a list of woods that gives their calorific outut & suitability for various types of heating / open fires.