Hi Helen
I'm sorry you feel disappointed, but do have a look at Alzi's message (below). It sounds like you may also be entitled to some compensation, which you could use to book the lounge independently.
Another option for meeting up with the other Manchester travellers is to try contacting them through this website and arranging a rendezvous time and location. Failing that, you may be able to spot each other's Just You luggage tags at the airport.
I understand your dilemma about which clothes to pack. I think a few jumpers and a warm jacket would definitely be an asset in the cooler evenings.
Have a great trip!
Olly your editor