Any advice on what model to go for? I'm definitely wanting the coupe model, petrol and a 2litre engine. I'd also like a sat nav and the other gadgets mentioned above. Other than that I have no clue on the models. Tried looking at comparison charts but it just went on about engine torque and other stuff I have no interest or clue about.
You don't seem that bothered or intersted in performance - which is absolutely fine, and my advice will reflect this.
If you chose a 3 Series Coupe with Professional Navigation, you will gain the 'cool screen' in the centre of the dash. I'd strongly advise this - because combined with another option, USB Interface, it also works as an excellent music centre and car control system. Cars built after September 08 with Pro Nav have a hard drive, higher resolution screen and much improved user interface.
There are two engines I'd suggest you look at - the 320i and the 325i.
The 320i is a 2 litre 16v 4 cylinder engine developing 170bhp. The 325i is actually a 3 litre 24v 6 cylinder engine developing 214bhp. However as its a direct injection engine it's actually stunningly economical for the engine size and has a combined mpg figure of almost 40mpg, so it's very much worth considering.
I normally brand it as a pointless engine because for those people into performance a 330i has the same engine with more power and the same running costs. However as a result the 325i is the unloved model in the range and you stand a much better chance of getting a much newer 325i than you do 330. There are also quite a lot of 325i about whereas the 330i is reasonably rare.
Both the 320i and the 325i have reliability issues so ensure you budget the circa £500 a year for the BMW warranty, then you dont need to worry about it.
Also be aware that a set of tyres for the cars on the 19 inch wheels is almost £1200.