July/August is the peak travel season across the Atlantic and prices are always high. Also I would advise against going to Vegas in July, it is very very hot. My wife nearly got a sun stroke and a bad cold because of the temperature shock from the nicely chilled buildings and the outside.
Current fares in the system: (used BD as plating carrier since we are in the BD forum

)
Code:
01JUL11**31JUL11/BD LONLAS/NSP;AT/TPM 5222/MPM 6344
LN FARE BASIS OW GBP RT B PEN DATES/DAYS AP MIN MAX R
01 CR2UA 8265 C - B28FEB - + - - - R
02 C77RT 7080 C - B28FEB - + - - 12M R
03 CFFGBW 5900 C - - - + - - 12M R
04 DFFGBW 4117 D - - - + - - 12M R
05 JRCGBW 3396 J + - - + + 2+ 12M R
06 Y77OW 1532 Y - - - + - - - R
07 Y77RT 3064 Y - - - + - 7 12M R
08 Y 1532 3064 Y - - - + - - 12M R
09 JNNGB4W 2100 J NRF - - +14+SU+ 12M R
10 S12 861 1722 S - B30MAY - + - - 12M+R
11 SFFGBW 796 1592 S - O31MAR - + - - 12M+R
12 BHWNCGBW 858 B NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
13 BHXNCGBW 828 B NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
14 MHWNCGBW 758 M NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
15 MHXNCGBW 728 M NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
16 HHWNCGBW 678 H NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
17 HHXNCGBW 648 H NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
18 QHWNCGBW 618 Q NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
19 QHXNCGBW 588 Q NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
20 VHWNCGBW 576 V NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
21 VHXNCGBW 546 V NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
22 WHWNCGBW 536 W NRF - 567+ +SU+ 12M R
S30JUN 21AUG
O31MAR -
23 WHXNCGBW 506 W NRF - 1234+ +SU+ 12M R
S30JUN 21AUG
O31MAR -