Romeo - there were no pilots current on the Harrier before it entered service either!! It's a matter of reintroducing skills on T.12's -not exactly rocket science. Similarily technicians don't have 'currency' on types -they rely on the manuals and training to achieve the task. As for the spares - I am not aware of any of the 80,000 line item spares as having been disposed off.
Any notion that the Harrier couldnt be put back into service is utter nonsense! BAe Systems employ a large number of former Harrier people both directly and under contract. Its worth pointing out that the Jump and SAM programme at Cottesmore was very heavily civilian so the knowledge is there.