so had my 156 a day or two now. Ive noticed that the temp gauge doesnt rwaly move. After being started a while it rises above 50. But not much above it. Driving on the main roads it shows similar. But if i drive throufg my village for a while it might go up to halfway between 50 and 90.
Snap! Mine was exactly the same
Thermostat stuck open is a really common fault and I'd definitely take it off and inspect at the very least, I wouldn't pay a dealer to diagnose first, as you can see for yourself. Looking in through the radiator hose fitting (with thermostat removed), you shouldn't see daylight through it. And you shouldn't be able to blow through it either.
If the thermostat has not been replaced before, you will need jubilee-type hose clips to replace the funky original clips which are several different designs and either non-reusable or an absolute pain to re-use without proper tools. You need two hose clips that are heater-hose sized, one hose clip that is radiator-hose sized (plus possibly another clip for the radiator bottom hose for when you drain the system), and one small hose clip (approx. 13mm) unless you manage to re-use the 'Clic' clamp on the bleeder hose (on top of the thermostat), which can be done because you can get to it with pliers.
Might sound like I'm making a fuss over nothing here, but it is really annoying to get part-way through the job and then find you can't finish because you're missing one hose-clamp and the original 'metal cable-tie' one is useless
As for bulb replacements - covered here several times recently - need 1.2W capless (wedge-base) bulbs. I'm pretty certain that you do have to take the gearlever surround off, then unscrew most other parts, remove the radio, etc. but it is worth it, particularly if you replace the other bulbs while you're there