right, this may sound silly, but where are the best locations to fit oil pressure and temperature sensors on the engine and how easy is it to do?

 

The oil pressure can only go on a T adapter with the oilo pressure switch.

As for temperature, depends where you want the reading to be from.

There will be great variations throughout the cooling system.

As a general rule i would say close to the the original

 

you can get an adaptor that fits between the block and the oil filter. It gives you threadded connections to fit oil temp and pressure gauge sensors.

I've never tried one my self but have a look on ebay.

 

If the temperature sensor for engine management it needs to go before the thermostat, ideally in the block. Look where the original is, if it has one.