Flight Profile for A320 EGLL-EGCC planned (not actual!):
WOBUN2F EGLL 000 1735
WOBUN2F 79% 060 1737
WOBUN2F BUR 060 1738
WOBUN2F 13% 080 1739
WOBUN2F 95% 150 174
WOBUN2F *1BUR 150 1742
WOBUN2F 24% 160 1743
WOBUN2F 65% 170 1743
DIRECT WOBUN170 1744
DIRECT 26% 180 1744
T420 WELIN 180 1746
T420 TIMPO 180 17:50
T420 *TNT1 180 1752
T420 54% 180 1754
T420 78% 160 1755
DAYNE 1B TNT 140 1755
DAYNE 1B *4TNT 090 1757
DAYNE 1B 17% 080 1757
DAYNE 1B DAYNE 040 1800
DAYNE 1B 10% 040 1800
DAYNE 1B MCT 007 1804
DAYNE 1B EGCC 000 1804
This detailed enough for you?
As you can see Max FL is FL180 from 1744 to 1754 so your cruise is about the 10 minute mark.