The best link would be a speedlink bus which goes from LGW to LHR. I would allow AT LEAST 2 hours to connect if she has all those bags. Since shortly after Sept 11, all pax travelling in transit from LGW to LHR have to cllect their bags at LGW and then re check them in at a FAST BAG DROP (which will be the best place to drop them. The bags can only be taken 2 and half hours before the flight departs, otherwise the person has to keep the bags with them.

They might be able to be thru checked but the bags wont be. So they will have a boarding pass and have a seat but the bags will need to be dropped off. (Customs regulations / security issue)