Join Date: Sep 2005
Location: HEL
Programs: AY Platinum, TK Elite, BT VIP, AA, BA, SK, DL, NT, WB + hotels
Posts: 8,799
Yes, you can enter the Schengen lounge.
If you don't use the automated passport control gates and the officer wants to know why you want to enter Finland, you can eg. tell him you're going to Jumbo (shopping centre with spa etc close to the airport) to pass the time as you have a longish five-hour layover.
After passport control, make sure to follow the signs carefully so you don't end up in Arrivals Hall 2B (after which you'd need to go through security to re-enter Airside). There's a passage (with customs) right after passport control that takes you directly to the Schengen Airside.
However, with PP, you may use the non-Schengen Almost@Home lounge.