Will have a look into those multi effects.The same problem as amps.The products variety our stores have is not good.
Also the Laney is all tube,why would it need a pre amp pedal ?
Because the tube amp has two different valves. A pre-amp valve and an output valve. Your guitar signal first gets pre-amp'd in the pre-amp valve and then goes through the effects (if the amp has those) and then goes through the output valve before getting played on the speaker. Therefore in short:
Guitar > [Pre-amp valve > EQ, effects, volume etc > output valve > Speaker].
Without Pre-amp pedal:
Guitar > EQ > [Pre-amp > effects, volume, etc > output valve > Speaker].
If the amp has effects loop, this problem gets mitigated in the following manner:
Guitar > [Pre-amp > FX loop out] > Pedal chain (EQ pedal will be somewhere in here) > [FX loop in > output valve > Speaker].
I think it would be better if you get an amp which has an onboard 3 band eq if you require it. Otherwise, get an overdrive pedal that has a 3 band eq on it.