My husband and I are celebrating 20 years of marriage next year and really wanted to take our 2 boys for a first trip to Europe. Due to uncertainty of Covid and no vaccine in sight at the moment, we were thinking maybe September or October. We want to pair it with London and would likely fly into London and out of Paris using Eurostar to connect from LDN to PAR. Weather wise, is September preferential over October? I know days will be getting shorter in October, mostly looking for months with less rain and hopefully less tourists. Thanks!