Also, the Myrtle Avenue photography spot is in fact a small grassy area, with some muddy bits.
This makes it very difficult for wheelchair users! You did mention limited mobility and you may mean this in terms of wheelchair use.
As mentioned there are normally like minded photographers there when the planes are landing on that runway. Keep close to them and strike up a conversation, it might be me......!
Remember Myrtle Avenue is suitable for photographs of landing aircraft on 27L only. Also when the planes are landing on the 27's (L and R) they do change runways at 15.00. This means a decamp to a different area, and possibly different issues. i.e. no parking and or long walk from Hatton Cross to the roundabout near BA
Also, similiar issues may occur if the planes are landing at the 09 end.