Thanks very much all - super helpful and will try to remember to update when I've done the ride! @T_Unit think it's this one you're looking for, but the bikely link doesn't seem to exist anymore and most of those I can find now go south of Slough through Maidenhead.. e.g. https://www.komoot.com/tour/211908029#previewMap. This looks promising though!
Was great, would strongly recommend the PedalNorth route, although we skipped the bit going through Slough so can't speak to that. And the bit going out of London was pretty grim until Uxbridge but don't think you can really escape that.
Thanks very much all - super helpful and will try to remember to update when I've done the ride! @T_Unit think it's this one you're looking for, but the bikely link doesn't seem to exist anymore and most of those I can find now go south of Slough through Maidenhead.. e.g. https://www.komoot.com/tour/211908029#previewMap. This looks promising though!