I've currently got the filter on the left side of the tank and the thermometer on the right hand side of the tank, Should I be moving it to the same side as the filter so it can push the heated water around more effectively?
it doesn't have to be directly next to the filter, just as long as it is not in a dead spot for water movement - otherwise it wont be as efficient (but will still work)
Also, would it be worth getting one of those stick on thermometers as it's one thing the setting the temperature and another thing to read it? And also where would that be best placed?
the stick-on ones are not very accurate. You can get cheap alcohol ones from eBay, or cheap didgital ones. The watch-out on the digital ones is that you should calibrate them first with a known standard (alcohol or magnesium based one) as they can be innacurate. As for setting the temp on the heater, you are correct to assume that this needs to be checked (hence why we use thermometers). The settings on heaters are notoriously innacurate and you will need to play around to get the right temp in the tank. Mine is set to 27c and that gives 25c water temp.
Should the bubbles be left on constantly? And how long would I leave the light on when I eventually get fish?
I assume you mean from the filter, or do you have an air pump? If from the filter then the additional air will help to aggitate the water surface and increasing oxygenation, although water movement is the most critical part here and you don't actual need the bubbles. If it's an additional air pump/stone then they are mainly used to provide an aesthetic effect, so up to you really.
I'm going to the LSF this evening to collect a testing kit and some water treatment.
these can be quite costly at a LFS (especially test kits). You might want to try eBay for a cheaper option. Also, Seachem Prime is possibly the most cost effecting dechlorinator you can buy (apart from pond ones) and not many LFS stock it. Again you can find it on eBay