This app was mentioned in 1 comment, with an average of 6.00 upvotes
> Not sure if taking the Heathrow to Paddington Express or the Connect. We're obviously older, so probably the Express. (I understand neither are covered by the Oyster).
Take the Connect, not the express. The express is not worth the extra money unless you are REALLY short on time.
> Are they clean-ish? How much do they cost? Maybe my search skills are lacking, but I didn't see those asked and answered before.
Use pub toilets, they are free and no-one will mind. There are also toilets in museums (which are free) and some large shops too. Trains station charge 30-50p as well.
see https://greatbritishpublictoiletmap.rca.ac.uk/ http://www.cityoflondon.gov.uk/services/transport-and-streets/clean-streets/Pages/Public-Toilets.aspx and there is a phone app - https://play.google.com/store/apps/details?id=com.arecadesign.toiletfinder&hl=en_GB
https://itunes.apple.com/us/app/city-toilet-finder/id956561927
> Anything else you'd tell your living out on the farm grandparents about a visit to London???
Without knowing what my grandparents interests and hobbies are, no ;)