"Passengers who present themselves later than 40 minutes prior to scheduled time of departure will not be accepted for travel, and will forfeit their seats"
http://www.easyjet.com/EN/Book/regulations.htm l#checkin
Please note that easyJet hand baggage regulations state that passengers are allowed to take onboard one piece of hand baggage. Although restrictions are being relaxed at some UK airports, easyJet will not consider changing its hand baggage policy until the rules and procedures at the majority of UK airports become clearer and more consistent.
"Pushchairs, buggies, and travel cots can be taken right up to the aircraft steps and/or door, where they will be taken by cabin crew and stored in the hold. You can however check it in with your baggage at check-in, if you wish to do so. Full size, non-collapsible prams cannot be accepted for travel.
Pushchairs, prams and travel cots do not form part of the baggage allowance and therefore no fee will be charged"