Would you recommend purchasing tickets on-site in London to fly round-trip to Malta and Poland? Or would you recommend purchasing tickets from US? Worried about costs.
If you're looking for discount airlines to those destinations, try whichbudget.com. It shows flights from Gatwick, Stansted, and Luton to both Poland and Malta. Check each airline for their luggage policies...many now charge for checked baggage, and impose heavy fees for anything above their weight limits.