Did a search today and found that the BMW UK website new car locator is now returning results for new M3 and M4 (even though the pictures on the search selections are still the F8x models!).
Using this you can see exactly what specs each dealer is getting and the lease/PCP costs. Interestingly within a 500 mile radius there was only one M3, but multiple M4s
G80 M3:
https://stock.bmw.co.uk/vehicle/IcQH...=016212&f=true
G82 M4:
https://stock.bmw.co.uk/results?f=dH...y_max=MTAwMA==
Just to note for non-UK viewers, as already well established elsewhere in this forum the UK only gets the Comp models.