Days out with terminally ill parent - Tips needed

(TL;DR - need ideas for days out in London that isn't dependent on good weather, and is 'cancer/access friendly' for my mother.)

My mother has terminal cancer with a prognosis of approx 3 months to live, currently receiving palliative care at home in London. 

Most days our quality time with her means spending time together at home with her because she is usually too ill. However, recently she has been wanting to do the occasional day out. We trialed a trip to Clissold Park last weekend and this was really successful. It really lifted her spirits and she really needs that right now. This weekend we will try Alexandra Palace.

As winter approaches park trips won't work and we will need to look at indoor/warmer activities and I'm drawing a blank.

I'm looking for ideas from anyone in the same situation; it would be a great help to us. Our criteria:

• Easy to drive to from Northeast London/ parking not a nightmare (avoiding public transport)
• Disabled/wheelchair access
• Needs to be a place where we can get to a toilet easily/disabled ideally
• Somewhere where if the weather is bad we can take her inside/ or indoors based
• The tough one - a place where she isn't too close to people since she is scared of catching covid whilst her immunity is compromised
• Another tough ask - a place where if she suddenly needs the toilet she can do so fairly easily (a shame because she loves the theatre etc)
  
  

Open to any suggestions even ones where not all the boxes are ticked above as we might find workarounds. It would mean the world to us!