The BA Amex Companion voucher scheme invariably only offers ABZ-LHR then LGW-MCO. We have done this route many times. We use a local transfer company and it has always gone well. The BA timings seem to allow for this : 3-4 hours between LHR arrival and LGW departure. We usually have time in the lounges at LGW/LHR before catching our next flight. The only hassle is collecting and then rechecking luggage.
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