ticket only events

I can understand why events such as GYS and gardens open etc choose to use ticket only, but I wish they could or would allow a small amount say 5-10 tickets on the gate with a blue badge. I have bad back problems and other things and the difficulty is that I only know on the day if I can manage to do something. It can change from being able to wander around quite easily , but can wake up and at worst it can be a difficulty just to get up so cant say in advance . If I am unable to walk far it is no use going and so now I either buy a ticket and may not be able to go (thus depriving someone else from going) or not get a ticket and on the day feel sad that I could have gone but no chance now. I would be happy to ring early on the day and sort of book in etc. When it was not ticketed I used to go to visit many gardens in the Yellow Book and of course besides enjoying myself very much and meeting many other garden lovers but often used to buy plants , have a coffee etc which all added to the money raised of course. , With friends I organise and have no problem driving so we can work on the premise that it is going ahead, unless I ring before 9am to say sorry have to cancel for today. There hasnt been many days I have had to cancel but just unable to say how things will be. Are any others in the same situation and what do they do about it?