No, we don't have a main breaker on UK panels. There is always a cartridge fuse (property of PoCo and sealed) before the meter, then in a TN-S or TN-C-S installation there will normally just be a double-pole main switch, then the individual MCBs.
A TT system will have a main RCD (or in older homes a voltage-operated ELCB), but that is purely for earth-leakage, it does not incorporate overload protection.
