10th SS did have a comprehensive fire-plan worked out and pre-registered for the entire Island and were actually considerably over-strength in terms of artillery and well-stocked with ammunition, as Guards Armoured Div found out at Elst and 43rd Div found out at Oosterhout. The volume of fire achieved was far higher than anything they had achieved in Normandy (due to fighting on top of their former supply depots).
And let us not forget that, while the Hun were enjoying[?] the advantage[?] of interior lines, (growing shorter with every step back towards
Der Vaterland ), they also - however perverse their reasoning - were motivated by the notion of protecting All That Is German.
By contrast, at this stage in the war, every Brit knew that victory was both inevitable, and none too far off in time. Add to that the recent re-badging of AA gunners (RAF as well as RA) to infantry, and the near-simultaneous widening of the UK age bracket for conscription (IIRC, by Sep '44 it spanned from 17yrs 6mths to 45 yrs of age), in response to unforeseen high losses in Normandy in Jul/Aug '44, and you can maybe begin to understand why a certain lack of
'gung ho' might have been detectable in Brit units/Fmns.
You could add to that an awareness that - whereas the Army that landed on D-Day had been training for 2 or 3 years for that day - the BCRS who made up much of the Brit force that was advancing on Arnhem had not been through anything remotely like as thorough prep as their D-Day predecessors (pre-deceasors?), whereas those who had fought and survived Normandy to take part in the 'pencil-like thrust' woulda been at least a little war-weary*.
Overlay on that the fact that the Brits had just enjoyed 'the great swan' after Falaise, during which they advanced pretty much unopposed (and arguably, therefore, weren't really Pursuing the Boche as Blucher pursued Napoleon's forces after Waterloo, The Pursuit being the decisive act in war) - and may well have convinced themselves that the war would be over by Xmas: only then to get an unexpected kick in the proverbials on the very border of Germany proper, to remind them that the game ain't over until it's over
* In
With The Jocks Peter White tells a really readable story about his experiences as a Pl Comd in a Jock mob recently arrived in theatre around the time of or just after the Arnhem op. Well worth a read in its own right, all the more interesting (IMHO) if read with the above context clearly in mind.