Now resolved - left the car at the local 'oileys' who said 'I should be able to do it late tomorrow' giving me time to source a replacement. Two hours later it arrived back on my drive done as he was delayed by a late delivery of parts for todays job, so he got and fitted a replacement Bosh motor.
Good service but no opportunity to do anything about sourcing a motor here or via here. BTW Bmminiparts.co.uk quoted £240 (inc VAT), a good saving over dealer price
Thanks Norman