Personally I wouldn’t bother with croft unless you’re actually passing the place. I know the local guys have put in a lot of hard work building the trails but I’ve ridden it 4 times and never impressed – v short and just doesn’t flow (nice rollers / jumps on an uphill section for example!). If it was on my doorstep I’d have a blast around it every now and then but not really worth travelling for…
Oxford to Cannock is about 90 miles from memory, and assuming you’re pretty close to A34 or M40 then about 80 miles is on the motorway, allowing 20 mins for the last 10 miles – pretty doable in an hour and a half within speed limits and assuming you’re not doing the M40/M42 junction at rush hour on a monday morning 😆