I have a vauxhall omega cd 2.2 with a fault code p1070 map sensor issue, does anyone know where this map sensor is located please ?

Your code 21 is just telling you that your left sidelight is out. The shaking and juddering is a different issue and needs a pro grade scan tool computer to see which sensor needs replacing.
21 Failure of left sidelight.

Vauxhall Astra Fault Codes - - Driving Test Tips

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Vauxhall Astra Fault Codes List ; 21, Failure of left sidelight. ; 22, Failure of right sidelight. ; 23, Failure of reversing light. ; 24, Failure of number plate ...

The reason of P1280 OBD-II Engine Trouble Code is Manifold Absolute Pressure/Barometric Pressure Circuit High Input. P1280 DTC reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.
1- Monitor M.A.P sensor voltage with a scanner or (Multimeter) backprobe (without removing the connector from the sensor) between ground and MAP signal 2- Engine off, ignition key on voltage should be near 5Volts 3- Engine running voltage should be under 1 volt 4- You can try a well-known MAP sensor 5- Could be wiring issues open circuit or short to ground.(While backprobing move wiring if voltage change on your meter this will tell you (wiring issues Hope it helps.

whats the symptom
is the rev going up and down by itself or some other issue
please elaberate

MAP (Manifold Absolute Pressure) sensor.

run fault code and look for faulty throttle position sensor or MAP/MAF sensors

0105 - MAP/BP Circuit Malfunction
0400 - EGR Flow Malfunction
0500 - Vehicle Speed Sensor Malfunction
1405 - DPFE Sensor Upstream Hose Off Or Plugged

Emisions related can be a lot of things. It would have logged a fault code to the computer. You need the vehiclescomputer scaned to reveal the fault. Could be lots of things (O2 sensor in the exhaust, airflow sensor, vacume leak, misfire, etc...) the only way to know will be to have the code extracted.

Finding the fault code will not clear the problem if you reset the system without finding the cause the light will just come on again or the fault code will not clear.
Anything related to brakes should be checked out by a garage/mechanic and not ignored.
Its probably just an abs sensor failed but its better to be safe than sorry.
Sorry for the lecture but I wouldnt like to see anyone hurt due to brake system failure.

Definition of Diagnostic Trouble Code P1296 Audi: Cooling system malfunction Chrysler: No 5 volts to MAP sensor Dodge: No 5 volts to MAP sensor Ford: Injector Multiple Faults - Bank 2 Jeep: No 5 volts to MAP sensor Lincoln: Injector Multiple Faults - Bank 2 Mazda: Injector Multiple Faults - Bank 2 Mercury: Injector Multiple Faults - Bank 2 Mitsubishi: MAP Sensor 5-Volt Supply Fault Volkswagen: Cooling system malfunction

I'm going to guess and say have the catalytic converter checked.  If that's it...it will also be giving you poor performance and mileage.  
Also replace the exhaust sensors and check the plugs for condition and gap.  Replace the air filter and pcv valve.