Car is running hot, should I be concerned?

Don't go by how hot the engine feels through the bonnet. Engines make a *lot* of heat as a by product of all the explosions they utilise to make them run. You should have a temperature gauge on the dashboard with this symbol:



That should be bang on in the middle with normal driving. Stop start city driving, especially on a warm day will likely push that up to 3/4, but it should never hit red. If you have enough coolant and it's still overheating (needle going into red) then your waterpump may be on the way out, and you'd want to get that fixed pretty soonish. No cooling and an overheated engine can lead to some pretty catastrophic stuff.

Mine one of this (from your picture) always shows in the middle. It goes to the middle when I switch the engiene on, could it be broke??

It is an old car, so I read the insulation over the bonnet isn't as good then as it is with new cars, so they do feel hotter. If I take the car up the motorway today and it does overheat, how is a way to cool is down as a temp solution or would I just need to call my break down cover?

Maybe get a better car. A Micra 2000 is a grannies car.

And no, when you switch the engine for the first time in the day, it shouldn't go straight up into the middle. It might if you switched your engine off, then came back 30 mins later.

I think you will need to have your car's thermostat to be replaced, The thermostat regulates the coolant flow in the engine so if it is faulty your car can heat up very quickly. Do have a good look at your radiator coolant and make sure that they are at optimum levels, read the owners manual for which coolant to be used . Take it to the garage to have its radiator's axial fan inspected, the water pump needs to be checked for any clogs and the radiator should be checked for leaks.
Do change your engine oil at recommended intervals as described by the owner's manual.

The car was serviced in May and had the oil replaced then. I'm servicing it again after it's MOT in September.
I'm going to pop it over to a garage disafternoon and get them to check to see if the coolant and radiator are running correctly just to be on the safe side I think.

Thats a good consideration, but do ask them to get the thermostat inspected it is the one that might be causing the problem.

If it really is overheating, and I am not convinced you know what you are talking about, try flushing the radiator. It is an old car so the the vents may be blocked.
You flush by disconnecting the top and bottom hose and holding a hosepipe in the radiator hole for the bottom hose. The water should exit from the top hose hole.
Do this for about 10 minutes

Another trick is remove the thermostat altogether. This allows greater water flow.
Whilst out the thermostat can be tested. Place in a pan of water and heat slowly.
It should open at about halfway to boiling.

Just got back from the mechanic. Everything is fine bar the fact my expansion box for my coolant is starting to go again!!

Thanks for the help, lucky I checked this x

Just got back from the mechanic. Everything is fine bar the fact my expansion box for my coolant is starting to go again!!

Thanks for the help, lucky I checked this x

It's unlikely to be the thermostat as these tend to stick open (more cooling) rather than closed (less cooling). To add to that, motorway driving is literally the best kind of driving for cars that 'run hot' as the engine is working relatively little and you're getting a huge air flow over the radiator. Compare this to running around town where you're revving it up and down all the time and you're spending a lot of time sitting still with no air flow over the radiator.

Unless the temperature sensor is bad, trust the temp gauge. A new sensor would be a couple of quid on eBay and very easy to fit if you wanted to trust the temp gauge 100%.

confused by what you mean by this, and i'd not listen to a single thing this 'mechanic' says, and find somewhere else to take your car in future.

the header tank it literally a plastic bottle with a pressure release cap, and 2 pipes a inlet and outlet for your coolant to cycle around the engine, your heater matrix and radiator etc.

there's literally nothing that can 'go' on the expansion tank, bar getting a leak (extremely unlikely its pretty thick plastic), the cap can become faulty so they system gets over or under pressurised ie it doesn't release pressure or allow air in if your running cold and there's a vacuum , new caps are a couple of quid, and the hoses to and from the tank can degrade and leak etc, but the tank itself is unlikely to have any problems, especially as you've recently replaced it.