You spend 20-25 minutes in the tunnel.
Easy check in process, no restrictions on what you can take on train.
Passport control is quick, bag scanners like at airport, swipe your ticket and you're away.
Think you're allowed two suitcases per person and usual customs allowances on tobacco and alcohol etc.
No ticket checks on train, no food trolley (there's a buffet car though).
At Lille, station isn't the easiest to navigate. There's a main road (Ave Le Corbusier) which splits the station in two. This road leads to town.
You might also find yourself in the open space underneath this road. follow the direction of the road away form the station and you should end up near town.
Ps: Advance Eurostar tickets were Ł27.50 pp each way!!

