I've never had any problems changing at Redhill. According to the (outdated) station map of Redhill station on National Rail Enquiries there were lifts on every platform. Disability regulations would make me think that there is a lift to the new platform 0.
Then you, sir, are extremely lucky! Redhill is a notoriously badly-managed node and suffers from frequent and serious delays and last-minute platform changes. I have just got home from a journey involving the place and my NDL train lost about 15 minutes on its approach to Redhill because of the inability of the railway to manage itself there. A NR leaf-buster stood in platform 2 for at least 12 minutes when it should have reversed and cleared the station immediately. Meanwhile trains were queueing outside and my train was switched from 2 to 1 at the last moment. It left nearly 25 late. This is cross-platform, but when (as is frequently the case) the switch is to 0, the interchange is not easy when the subway is clogged with incoming passengers. With 12 car platforms, a secondary interchange route at the north end of the platforms is sorely needed, especially given the frequent last-minute platform changes which give passengers at the north ends almost no chance of making the interchange in time (given, also, the sporadic and unreliable/inaudible live P.A. use there!).
Earlier today I had to abandon the NDL at Dorking Deepdene (towards Redhill) when a train stood in the platform there and we were told a person had been taken ill.
Three police cars,
two ambulances and a GWR pick-up were parked outside the station (for
one ill person - so much for stretched emergency services!). This evening our guard announced that a person had been taken ill earlier at Gomshall(?). Why, we wondered, was there such a massive emergency services presence at Dorking if the stricken train was at Gomshall (immediately next to the A25 road), and why was the train at Deepdene being held there for so long if it wasn't the train carrying the ill person (it would have been ahead of, not behind, the affected train)? The usual shambolic, inconsistent (or totally absent) information regime prevailed. Incidentally, the platform DMIs at Deepdene appear to work on the basis that all trains are assumed to have left on time, as they disappear from the screens after/at the scheduled departure time, to be replaced by the next train, whether they have actually left or not!! For example, at 1206, the DMI showed the train in the platform as being the 1211 when it was obviously the preceding one. I have seen at least two people on previous occasions get up to the platform, see the next train described as being half an hour away and leave again (presumably for a taxi or bus instead), not realising that their train is actually only a couple of minutes late and still to arrive! My train this evening at Deepdene was also being described as the following one even as we alighted onto the platform (about 23 late).
All this with 2TPH - the crazy idea of 3TPH would presumably lead to complete chaos!