Hungarian low cost carrier Wizz Air offers cheap flights from UK to Belgrade. Tickets from London (Luton) from only 32.98 GBP round trip.
Sample travel dates:
October, November and December 2015.
How to book:
Go to Wizzair.com and choose the routing and dates from above.
Baggage during the trip:
One cabin bag per passenger with maximum dimensions of 42cm x 32cm x 25cm. To get the lowest rates you have to be a member of Wizz Discount Club (WDC).