For awareness if visitors have not picked this up elsewhere there's a strike due to affect TfL services next week for 4 whole days with impacts on the eve and morning after.

It is possible that some last minute negotiations may find a compromise and the strike is postponed or cancelled, but there's no sign of that yet.

For Heathrow, if the strike goes ahead, the Piccadilly line (and all other tube lines) will likely have no service. Elizabeth line should run but will be busy and some stations may be closed due to lack of staff.

For the detail see https://tfl.gov.uk/campaign/strikes